/src/vlc/modules/packetizer/mpeg4video.c

Source
/*****************************************************************************
 * mpeg4video.c: mpeg 4 video packetizer
 *****************************************************************************
 * Copyright (C) 2001-2006 VLC authors and VideoLAN
 *
 * Authors: Gildas Bazin <gbazin@videolan.org>
 *          Laurent Aimar <fenrir@via.ecp.fr>
 *          Eric Petit <titer@videolan.org>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/

/*****************************************************************************
 * Preamble
 *****************************************************************************/

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <vlc_common.h>
#include <vlc_plugin.h>
#include <vlc_sout.h>
#include <vlc_codec.h>
#include <vlc_block.h>

#include <vlc_bits.h>
#include <vlc_block_helper.h>
#include "packetizer_helper.h"
#include "startcode_helper.h"
#include "h26x_nal_common.h"

/*****************************************************************************
 * Module descriptor
 *****************************************************************************/
static int  Open ( vlc_object_t * );
static void Close( vlc_object_t * );

vlc_module_begin ()
    set_subcategory( SUBCAT_SOUT_PACKETIZER )
    set_description( N_("MPEG4 video packetizer") )
    set_capability( "video packetizer", 50 )
    set_callbacks( Open, Close )
vlc_module_end ()

/****************************************************************************
 * Local prototypes
 ****************************************************************************/
typedef struct
{
    /*
     * Input properties
     */
    packetizer_t packetizer;

    /*
     * Common properties
     */
    vlc_tick_t i_interpolated_pts;
    vlc_tick_t i_interpolated_dts;
    vlc_tick_t i_last_ref_pts;
    int64_t i_last_time_ref;
    int64_t i_time_ref;
    int64_t i_last_time;
    int64_t i_last_timeincr;

    unsigned int i_flags;

    int         i_fps_num;
    int         i_fps_den;

    bool  b_frame;

    /* Current frame being built */
    block_t    *p_frame;
    block_t    **pp_last;
} decoder_sys_t;

static block_t *Packetize( decoder_t *, block_t ** );
static void PacketizeFlush( decoder_t * );

static void PacketizeReset( void *p_private, bool b_broken );
static block_t *PacketizeParse( void *p_private, bool *pb_ts_used, block_t * );
static int PacketizeValidate( void *p_private, block_t * );

static block_t *ParseMPEGBlock( decoder_t *, block_t * );
static int ParseVOL( decoder_t *, es_format_t *, uint8_t *, int );
static int ParseVO( decoder_t *, block_t * );
static int ParseVOP( decoder_t *, block_t * );
static int vlc_log2( unsigned int );

#define VIDEO_OBJECT_MASK                       0x01f
#define VIDEO_OBJECT_LAYER_MASK                 0x00f

#define VIDEO_OBJECT_START_CODE                 0x100
#define VIDEO_OBJECT_LAYER_START_CODE           0x120
#define RESERVED_START_CODE                     0x130
#define VISUAL_OBJECT_SEQUENCE_START_CODE       0x1b0
#define VISUAL_OBJECT_SEQUENCE_END_CODE         0x1b1
#define USER_DATA_START_CODE                    0x1b2
#define GROUP_OF_VOP_START_CODE                 0x1b3
#define VIDEO_SESSION_ERROR_CODE                0x1b4
#define VISUAL_OBJECT_START_CODE                0x1b5
#define VOP_START_CODE                          0x1b6
#define FACE_OBJECT_START_CODE                  0x1ba
#define FACE_OBJECT_PLANE_START_CODE            0x1bb
#define MESH_OBJECT_START_CODE                  0x1bc
#define MESH_OBJECT_PLANE_START_CODE            0x1bd
#define STILL_TEXTURE_OBJECT_START_CODE         0x1be
#define TEXTURE_SPATIAL_LAYER_START_CODE        0x1bf
#define TEXTURE_SNR_LAYER_START_CODE            0x1c0

static const uint8_t p_mp4v_startcode[3] = { 0x00, 0x00, 0x01 };

/*****************************************************************************
 * Open: probe the packetizer and return score
 *****************************************************************************/
static int Open( vlc_object_t *p_this )
{
    decoder_t     *p_dec = (decoder_t*)p_this;
    decoder_sys_t *p_sys;

    if( p_dec->fmt_in->i_codec != VLC_CODEC_MP4V )
        return VLC_EGENERIC;

    /* Allocate the memory needed to store the decoder's structure */
    if( ( p_dec->p_sys = p_sys = malloc( sizeof(decoder_sys_t) ) ) == NULL )
        return VLC_ENOMEM;
    memset( p_sys, 0, sizeof(decoder_sys_t) );

    /* Misc init */
    packetizer_Init( &p_sys->packetizer,
                     p_mp4v_startcode, sizeof(p_mp4v_startcode), startcode_FindAnnexB,
                     NULL, 0, 4,
                     PacketizeReset, PacketizeParse, PacketizeValidate, NULL,
                     p_dec );

    p_sys->p_frame = NULL;
    p_sys->pp_last = &p_sys->p_frame;

    /* Setup properties */
    es_format_Copy( &p_dec->fmt_out, p_dec->fmt_in );
    p_dec->fmt_out.i_codec = VLC_CODEC_MP4V;

    if( p_dec->fmt_out.i_extra )
    {
        /* We have a vol */
        msg_Dbg( p_dec, "opening with vol size: %zu", p_dec->fmt_out.i_extra );
        ParseVOL( p_dec, &p_dec->fmt_out,
                  p_dec->fmt_out.p_extra, p_dec->fmt_out.i_extra );
    }

    /* Set callback */
    p_dec->pf_packetize = Packetize;
    p_dec->pf_flush = PacketizeFlush;
    p_dec->pf_get_cc = NULL;

    return VLC_SUCCESS;
}

/*****************************************************************************
 * Close: clean up the packetizer
 *****************************************************************************/
static void Close( vlc_object_t *p_this )
{
    decoder_t *p_dec = (decoder_t*)p_this;
    decoder_sys_t *p_sys = p_dec->p_sys;

    packetizer_Clean( &p_sys->packetizer );
    if( p_sys->p_frame )
        block_ChainRelease( p_sys->p_frame );
    free( p_sys );
}

/****************************************************************************
 * Packetize: the whole thing
 ****************************************************************************/
static block_t *Packetize( decoder_t *p_dec, block_t **pp_block )
{
    decoder_sys_t *p_sys = p_dec->p_sys;

    return packetizer_Packetize( &p_sys->packetizer, pp_block );
}

static void PacketizeFlush( decoder_t *p_dec )
{
    decoder_sys_t *p_sys = p_dec->p_sys;

    packetizer_Flush( &p_sys->packetizer );
}

/*****************************************************************************
 * Helpers:
 *****************************************************************************/
static void PacketizeReset( void *p_private, bool b_flush )
{
    decoder_t *p_dec = p_private;
    decoder_sys_t *p_sys = p_dec->p_sys;

    if( b_flush )
    {
        if( p_sys->p_frame )
            block_ChainRelease( p_sys->p_frame );
        p_sys->p_frame = NULL;
        p_sys->pp_last = &p_sys->p_frame;
    }

    p_sys->i_interpolated_pts =
    p_sys->i_interpolated_dts =
    p_sys->i_last_ref_pts = VLC_TICK_INVALID;

    p_sys->i_last_time_ref =
    p_sys->i_time_ref =
    p_sys->i_last_time =
    p_sys->i_last_timeincr = 0;
}

static block_t *PacketizeParse( void *p_private, bool *pb_ts_used, block_t *p_block )
{
    decoder_t *p_dec = p_private;
    const vlc_tick_t i_dts = p_block->i_dts;
    const vlc_tick_t i_pts = p_block->i_pts;

    block_t *p_au = ParseMPEGBlock( p_dec, p_block );

    *pb_ts_used = p_au &&  p_au->i_dts == i_dts && p_au->i_pts == i_pts;

    return p_au;
}


static int PacketizeValidate( void *p_private, block_t *p_au )
{
    decoder_t *p_dec = p_private;
    decoder_sys_t *p_sys = p_dec->p_sys;

    /* We've just started the stream, wait for the first PTS.
     * We discard here so we can still get the sequence header. */
    if( p_sys->i_interpolated_pts == VLC_TICK_INVALID &&
        p_sys->i_interpolated_dts == VLC_TICK_INVALID )
    {
        msg_Dbg( p_dec, "need a starting pts/dts" );
        return VLC_EGENERIC;
    }

    /* When starting the stream we can have the first frame with
     * a null DTS (i_interpolated_pts is initialized to 0) */
    if( p_au->i_dts == VLC_TICK_INVALID )
        p_au->i_dts = p_au->i_pts;
    return VLC_SUCCESS;
}

/*****************************************************************************
 * ParseMPEGBlock: Re-assemble fragments into a block containing a picture
 *****************************************************************************/
static block_t *ParseMPEGBlock( decoder_t *p_dec, block_t *p_frag )
{
    decoder_sys_t *p_sys = p_dec->p_sys;
    block_t *p_pic = NULL;

    if( p_frag->i_buffer < 4 )
        return p_frag;

    const uint32_t i_startcode = GetDWBE( p_frag->p_buffer );
    if( i_startcode == VISUAL_OBJECT_SEQUENCE_START_CODE ||
        i_startcode == VISUAL_OBJECT_SEQUENCE_END_CODE ||
        i_startcode == USER_DATA_START_CODE )
    {   /* VOS and USERDATA */
#if 0
        /* Remove VOS start/end code from the original stream */
        block_Release( p_frag );
#else
        /* Append the block for now since ts/ps muxers rely on VOL
         * being present in the stream */
        block_ChainLastAppend( &p_sys->pp_last, p_frag );
#endif
        return NULL;
    }
    else if( i_startcode >= VIDEO_OBJECT_LAYER_START_CODE &&
             i_startcode < RESERVED_START_CODE )
    {
        /* Copy the complete VOL */
        if( (size_t)p_dec->fmt_out.i_extra != p_frag->i_buffer ||
           ( p_frag->i_buffer && memcmp(p_dec->fmt_out.p_extra,
                                        p_frag->p_buffer, p_frag->i_buffer) ) )
        {
            void *p_realloc = realloc( p_dec->fmt_out.p_extra, p_frag->i_buffer );
            if( p_realloc )
            {
                p_dec->fmt_out.p_extra = p_realloc;
                p_dec->fmt_out.i_extra = p_frag->i_buffer;
                memcpy( p_realloc, p_frag->p_buffer, p_frag->i_buffer );
            }
        }
        ParseVOL( p_dec, &p_dec->fmt_out,
                  p_dec->fmt_out.p_extra, p_dec->fmt_out.i_extra );

#if 0
        /* Remove from the original stream */
        block_Release( p_frag );
#else
        /* Append the block for now since ts/ps muxers rely on VOL
         * being present in the stream */
        block_ChainLastAppend( &p_sys->pp_last, p_frag );
#endif
        return NULL;
    }
    else
    {
        if( !p_dec->fmt_out.i_extra )
        {
            msg_Warn( p_dec, "waiting for VOL" );
            block_Release( p_frag );
            return NULL;
        }

        /* Append the block */
        block_ChainLastAppend( &p_sys->pp_last, p_frag );
    }

    if( i_startcode == VISUAL_OBJECT_START_CODE )
    {
        ParseVO( p_dec, p_frag );
    }
    else
    if( i_startcode == VOP_START_CODE &&
        ParseVOP( p_dec, p_frag ) == VLC_SUCCESS )
    {
        /* We are dealing with a VOP */
        p_pic = block_ChainGather( p_sys->p_frame );
        p_pic->i_flags = p_sys->i_flags;
        p_pic->i_pts = p_sys->i_interpolated_pts;
        p_pic->i_dts = p_sys->i_interpolated_dts;

#if 0
    msg_Err( p_dec, "output dts/pts (%"PRId64",%"PRId64")", p_pic->i_dts, p_pic->i_pts );
#endif
        /* Reset context */
        p_sys->p_frame = NULL;
        p_sys->pp_last = &p_sys->p_frame;
    }

    return p_pic;
}

/* ParseVOL: */
static int ParseVOL( decoder_t *p_dec, es_format_t *fmt,
                     uint8_t *p_vol, int i_vol )
{
    decoder_sys_t *p_sys = p_dec->p_sys;
    int i_vo_ver_id, i_shape;
    h26x_aspect_ratio_t ar;
    bs_t s;

    for( ;; )
    {
        if( i_vol <= 5 )
            return VLC_EGENERIC;

        uint32_t i_startcode = GetDWBE( p_vol );
        if( i_startcode >= VIDEO_OBJECT_LAYER_START_CODE &&
            i_startcode < RESERVED_START_CODE )
            break;

        p_vol++; i_vol--;
    }

    bs_init( &s, &p_vol[4], i_vol - 4 );

    bs_skip( &s, 1 );   /* random access */
    bs_skip( &s, 8 );   /* vo_type */
    if( bs_read1( &s ) )
    {
        i_vo_ver_id = bs_read( &s, 4 );
        bs_skip( &s, 3 );
    }
    else
    {
        i_vo_ver_id = 1;
    }
    ar.aspect_ratio_idc = bs_read( &s, 4 ) & 0xf;
    if( ar.aspect_ratio_idc == 0xf )
    {
        ar.aspect_ratio_idc = 0xff; // was only coded on 4 bits in MPEG4
        ar.sar_width = bs_read( &s, 8 );
        ar.sar_height = bs_read( &s, 8 );
    }
    if(!p_dec->fmt_in->video.i_sar_num ||
       !p_dec->fmt_in->video.i_sar_den)
    {
        h26x_get_aspect_ratio(&ar,
                              &fmt->video.i_sar_num,
                              &fmt->video.i_sar_den);
    }

    if( bs_read1( &s ) )
    {
        /* vol control parameter */
        bs_skip( &s, 2 ); /* chroma_format */
        bs_skip( &s, 1 ); /* low_delay */

        if( bs_read1( &s ) )
        {
            bs_skip( &s, 16 );
            bs_skip( &s, 16 );
            bs_skip( &s, 16 );
            bs_skip( &s, 3 );
            bs_skip( &s, 11 );
            bs_skip( &s, 1 );
            bs_skip( &s, 16 );
        }
    }
    /* shape 0->RECT, 1->BIN, 2->BIN_ONLY, 3->GRAY */
    i_shape = bs_read( &s, 2 );
    if( i_shape == 3 && i_vo_ver_id != 1 )
    {
        bs_skip( &s, 4 );
    }

    if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */

    p_sys->i_fps_num = bs_read( &s, 16 ); /* Time increment resolution*/
    if( !p_sys->i_fps_num ) p_sys->i_fps_num = 1;

    if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */

    if( bs_read1( &s ) )
    {
        int i_time_increment_bits = vlc_log2( p_sys->i_fps_num - 1 ) + 1;

        if( i_time_increment_bits < 1 ) i_time_increment_bits = 1;

        p_sys->i_fps_den = bs_read( &s, i_time_increment_bits );
    }
    if( i_shape == 0 )
    {
        bs_skip( &s, 1 );
        fmt->video.i_width = bs_read( &s, 13 );
        bs_skip( &s, 1 );
        fmt->video.i_height= bs_read( &s, 13 );
        bs_skip( &s, 1 );
    }

    return VLC_SUCCESS;
}

static int ParseVO( decoder_t *p_dec, block_t *p_vo )
{
    bs_t s;
    bs_init( &s, &p_vo->p_buffer[4], p_vo->i_buffer - 4 );
    if( bs_read1( &s ) )
        bs_skip( &s, 7 );

    const uint8_t visual_object_type = bs_read( &s, 4 );
    if( visual_object_type == 1 /* video ID */ ||
        visual_object_type == 2 /* still texture ID */ )
    {
        h26x_colour_description_t colour =
        {
            .colour_primaries = 1,
            .transfer_characteristics = 1,
            .matrix_coeffs = 1,
            .full_range_flag = 0,
        };
        if( bs_read1( &s ) ) /* video_signal_type */
        {
            bs_skip( &s, 3 );
            colour.full_range_flag = bs_read( &s, 1 );
            if( bs_read( &s, 1 ) ) /* colour description */
            {
                colour.colour_primaries = bs_read( &s, 8 );
                colour.transfer_characteristics = bs_read( &s, 8 );
                colour.matrix_coeffs = bs_read( &s, 8 );
            }
        }

        if( p_dec->fmt_in->video.primaries == COLOR_PRIMARIES_UNDEF )
        {
            h26x_get_colorimetry( &colour,
                                  &p_dec->fmt_out.video.primaries,
                                  &p_dec->fmt_out.video.transfer,
                                  &p_dec->fmt_out.video.space,
                                  &p_dec->fmt_out.video.color_range );
        }
    }

    return VLC_SUCCESS;
}

static int ParseVOP( decoder_t *p_dec, block_t *p_vop )
{
    decoder_sys_t *p_sys = p_dec->p_sys;
    int64_t i_time_increment, i_time_ref;
    int i_modulo_time_base = 0, i_time_increment_bits;
    bs_t s;

    bs_init( &s, &p_vop->p_buffer[4], p_vop->i_buffer - 4 );

    switch( bs_read( &s, 2 ) )
    {
    case 0:
        p_sys->i_flags = BLOCK_FLAG_TYPE_I;
        break;
    case 1:
        p_sys->i_flags = BLOCK_FLAG_TYPE_P;
        break;
    case 2:
        p_sys->i_flags = BLOCK_FLAG_TYPE_B;
        p_sys->b_frame = true;
        break;
    case 3: /* gni ? */
        p_sys->i_flags = BLOCK_FLAG_TYPE_PB;
        break;
    }

    while( bs_read( &s, 1 ) ) i_modulo_time_base++;
    if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */

    /* VOP time increment */
    i_time_increment_bits = vlc_log2(p_sys->i_fps_num - 1) + 1;
    if( i_time_increment_bits < 1 ) i_time_increment_bits = 1;
    i_time_increment = bs_read( &s, i_time_increment_bits );

    /* Interpolate PTS/DTS */
    if( !(p_sys->i_flags & BLOCK_FLAG_TYPE_B) )
    {
        p_sys->i_last_time_ref = p_sys->i_time_ref;
        p_sys->i_time_ref +=
            (i_modulo_time_base * p_sys->i_fps_num);
        i_time_ref = p_sys->i_time_ref;
    }
    else
    {
        i_time_ref = p_sys->i_last_time_ref +
            (i_modulo_time_base * p_sys->i_fps_num);
    }

    int64_t i_time_diff = (i_time_ref + i_time_increment) - (p_sys->i_last_time + p_sys->i_last_timeincr);
    if( p_sys->i_fps_num && i_modulo_time_base == 0 && i_time_diff < 0 && -i_time_diff > p_sys->i_fps_num )
    {
        msg_Warn(p_dec, "missing modulo_time_base update");
        i_modulo_time_base += -i_time_diff / p_sys->i_fps_num;
        p_sys->i_time_ref += (i_modulo_time_base * p_sys->i_fps_num);
        p_sys->i_time_ref += p_sys->i_last_timeincr % p_sys->i_fps_num;
        i_time_ref = p_sys->i_time_ref;
    }

    if( p_sys->i_fps_num < 5 && /* Work-around buggy streams */
        p_dec->fmt_in->video.i_frame_rate > 0 &&
        p_dec->fmt_in->video.i_frame_rate_base > 0 )
    {
        p_sys->i_interpolated_pts += vlc_tick_from_samples(
        p_dec->fmt_in->video.i_frame_rate_base,
        p_dec->fmt_in->video.i_frame_rate);
    }
    else if( p_sys->i_fps_num )
    {
        i_time_diff = (i_time_ref + i_time_increment) - (p_sys->i_last_time + p_sys->i_last_timeincr);
        p_sys->i_interpolated_pts += vlc_tick_from_samples( i_time_diff, p_sys->i_fps_num );
    }

#if 0
    msg_Err( p_dec, "interp dts/pts (%"PRId64",%"PRId64"), dts/pts (%"PRId64",%"PRId64") %"PRId64" mod %d inc %"PRId64,
             p_sys->i_interpolated_dts, p_sys->i_interpolated_pts,
             p_vop->i_dts, p_vop->i_pts, p_sys->i_time_ref, i_modulo_time_base, i_time_increment );
#endif

    p_sys->i_last_time = i_time_ref;
    p_sys->i_last_timeincr = i_time_increment;

    /* Correct interpolated dts when we receive a new pts/dts */
    if( p_vop->i_pts != VLC_TICK_INVALID )
        p_sys->i_interpolated_pts = p_vop->i_pts;
    if( p_vop->i_dts != VLC_TICK_INVALID )
        p_sys->i_interpolated_dts = p_vop->i_dts;

    if( (p_sys->i_flags & BLOCK_FLAG_TYPE_B) || !p_sys->b_frame )
    {
        /* Trivial case (DTS == PTS) */

        p_sys->i_interpolated_dts = p_sys->i_interpolated_pts;

        if( p_vop->i_pts != VLC_TICK_INVALID )
            p_sys->i_interpolated_dts = p_vop->i_pts;
        if( p_vop->i_dts != VLC_TICK_INVALID )
            p_sys->i_interpolated_dts = p_vop->i_dts;

        p_sys->i_interpolated_pts = p_sys->i_interpolated_dts;
    }
    else
    {
        if( p_sys->i_last_ref_pts != VLC_TICK_INVALID )
            p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;

        p_sys->i_last_ref_pts = p_sys->i_interpolated_pts;
    }

    return VLC_SUCCESS;
}

/* look at libavutil av_log2 ;) */
static int vlc_log2( unsigned int v )
{
    int n = 0;
    static const int vlc_log2_table[16] =
    {
        0,0,1,1,2,2,2,2, 3,3,3,3,3,3,3,3
    };

    if( v&0xffff0000 )
    {
        v >>= 16;
        n += 16;
    }
    if( v&0xff00 )
    {
        v >>= 8;
        n += 8;
    }
    if( v&0xf0 )
    {
        v >>= 4;
        n += 4;
    }
    n += vlc_log2_table[v];

    return n;
}

Coverage Report

Created: 2026-02-26 08:10

Line	Count	Source
1		/*****************************************************************************
2		* mpeg4video.c: mpeg 4 video packetizer
3		*****************************************************************************
4		* Copyright (C) 2001-2006 VLC authors and VideoLAN
5		*
6		* Authors: Gildas Bazin <gbazin@videolan.org>
7		* Laurent Aimar <fenrir@via.ecp.fr>
8		* Eric Petit <titer@videolan.org>
9		*
10		* This program is free software; you can redistribute it and/or modify it
11		* under the terms of the GNU Lesser General Public License as published by
12		* the Free Software Foundation; either version 2.1 of the License, or
13		* (at your option) any later version.
14		*
15		* This program is distributed in the hope that it will be useful,
16		* but WITHOUT ANY WARRANTY; without even the implied warranty of
17		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18		* GNU Lesser General Public License for more details.
19		*
20		* You should have received a copy of the GNU Lesser General Public License
21		* along with this program; if not, write to the Free Software Foundation,
22		* Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
23		*****************************************************************************/
24
25		/*****************************************************************************
26		* Preamble
27		*****************************************************************************/
28
29		#ifdef HAVE_CONFIG_H
30		# include "config.h"
31		#endif
32
33		#include <vlc_common.h>
34		#include <vlc_plugin.h>
35		#include <vlc_sout.h>
36		#include <vlc_codec.h>
37		#include <vlc_block.h>
38
39		#include <vlc_bits.h>
40		#include <vlc_block_helper.h>
41		#include "packetizer_helper.h"
42		#include "startcode_helper.h"
43		#include "h26x_nal_common.h"
44
45		/*****************************************************************************
46		* Module descriptor
47		*****************************************************************************/
48		static int Open ( vlc_object_t * );
49		static void Close( vlc_object_t * );
50
51	104	vlc_module_begin ()
52	52	set_subcategory( SUBCAT_SOUT_PACKETIZER )
53	52	set_description( N_("MPEG4 video packetizer") )
54	52	set_capability( "video packetizer", 50 )
55	104	set_callbacks( Open, Close )
56	52	vlc_module_end ()
57
58		/****************************************************************************
59		* Local prototypes
60		****************************************************************************/
61		typedef struct
62		{
63		/*
64		* Input properties
65		*/
66		packetizer_t packetizer;
67
68		/*
69		* Common properties
70		*/
71		vlc_tick_t i_interpolated_pts;
72		vlc_tick_t i_interpolated_dts;
73		vlc_tick_t i_last_ref_pts;
74		int64_t i_last_time_ref;
75		int64_t i_time_ref;
76		int64_t i_last_time;
77		int64_t i_last_timeincr;
78
79		unsigned int i_flags;
80
81		int i_fps_num;
82		int i_fps_den;
83
84		bool b_frame;
85
86		/* Current frame being built */
87		block_t *p_frame;
88		block_t **pp_last;
89		} decoder_sys_t;
90
91		static block_t Packetize( decoder_t , block_t ** );
92		static void PacketizeFlush( decoder_t * );
93
94		static void PacketizeReset( void *p_private, bool b_broken );
95		static block_t PacketizeParse( void p_private, bool pb_ts_used, block_t );
96		static int PacketizeValidate( void p_private, block_t );
97
98		static block_t ParseMPEGBlock( decoder_t , block_t * );
99		static int ParseVOL( decoder_t , es_format_t , uint8_t *, int );
100		static int ParseVO( decoder_t , block_t );
101		static int ParseVOP( decoder_t , block_t );
102		static int vlc_log2( unsigned int );
103
104		#define VIDEO_OBJECT_MASK 0x01f
105		#define VIDEO_OBJECT_LAYER_MASK 0x00f
106
107		#define VIDEO_OBJECT_START_CODE 0x100
108	93.6k	#define VIDEO_OBJECT_LAYER_START_CODE 0x120
109	34.3k	#define RESERVED_START_CODE 0x130
110	0	#define VISUAL_OBJECT_SEQUENCE_START_CODE 0x1b0
111	0	#define VISUAL_OBJECT_SEQUENCE_END_CODE 0x1b1
112	0	#define USER_DATA_START_CODE 0x1b2
113		#define GROUP_OF_VOP_START_CODE 0x1b3
114		#define VIDEO_SESSION_ERROR_CODE 0x1b4
115	0	#define VISUAL_OBJECT_START_CODE 0x1b5
116	0	#define VOP_START_CODE 0x1b6
117		#define FACE_OBJECT_START_CODE 0x1ba
118		#define FACE_OBJECT_PLANE_START_CODE 0x1bb
119		#define MESH_OBJECT_START_CODE 0x1bc
120		#define MESH_OBJECT_PLANE_START_CODE 0x1bd
121		#define STILL_TEXTURE_OBJECT_START_CODE 0x1be
122		#define TEXTURE_SPATIAL_LAYER_START_CODE 0x1bf
123		#define TEXTURE_SNR_LAYER_START_CODE 0x1c0
124
125		static const uint8_t p_mp4v_startcode[3] = { 0x00, 0x00, 0x01 };
126
127		/*****************************************************************************
128		* Open: probe the packetizer and return score
129		*****************************************************************************/
130		static int Open( vlc_object_t *p_this )
131	28.4k	{
132	28.4k	decoder_t p_dec = (decoder_t)p_this;
133	28.4k	decoder_sys_t *p_sys;
134
135	28.4k	if( p_dec->fmt_in->i_codec != VLC_CODEC_MP4V )
136	27.5k	return VLC_EGENERIC;
137
138		/* Allocate the memory needed to store the decoder's structure */
139	856	if( ( p_dec->p_sys = p_sys = malloc( sizeof(decoder_sys_t) ) ) == NULL )
140	0	return VLC_ENOMEM;
141	856	memset( p_sys, 0, sizeof(decoder_sys_t) );
142
143		/* Misc init */
144	856	packetizer_Init( &p_sys->packetizer,
145	856	p_mp4v_startcode, sizeof(p_mp4v_startcode), startcode_FindAnnexB,
146	856	NULL, 0, 4,
147	856	PacketizeReset, PacketizeParse, PacketizeValidate, NULL,
148	856	p_dec );
149
150	856	p_sys->p_frame = NULL;
151	856	p_sys->pp_last = &p_sys->p_frame;
152
153		/* Setup properties */
154	856	es_format_Copy( &p_dec->fmt_out, p_dec->fmt_in );
155	856	p_dec->fmt_out.i_codec = VLC_CODEC_MP4V;
156
157	856	if( p_dec->fmt_out.i_extra )
158	610	{
159		/* We have a vol */
160	610	msg_Dbg( p_dec, "opening with vol size: %zu", p_dec->fmt_out.i_extra );
161	610	ParseVOL( p_dec, &p_dec->fmt_out,
162	610	p_dec->fmt_out.p_extra, p_dec->fmt_out.i_extra );
163	610	}
164
165		/* Set callback */
166	856	p_dec->pf_packetize = Packetize;
167	856	p_dec->pf_flush = PacketizeFlush;
168	856	p_dec->pf_get_cc = NULL;
169
170	856	return VLC_SUCCESS;
171	856	}
172
173		/*****************************************************************************
174		* Close: clean up the packetizer
175		*****************************************************************************/
176		static void Close( vlc_object_t *p_this )
177	856	{
178	856	decoder_t p_dec = (decoder_t)p_this;
179	856	decoder_sys_t *p_sys = p_dec->p_sys;
180
181	856	packetizer_Clean( &p_sys->packetizer );
182	856	if( p_sys->p_frame )
183	0	block_ChainRelease( p_sys->p_frame );
184	856	free( p_sys );
185	856	}
186
187		/****************************************************************************
188		* Packetize: the whole thing
189		****************************************************************************/
190		static block_t Packetize( decoder_t p_dec, block_t **pp_block )
191	0	{
192	0	decoder_sys_t *p_sys = p_dec->p_sys;
193
194	0	return packetizer_Packetize( &p_sys->packetizer, pp_block );
195	0	}
196
197		static void PacketizeFlush( decoder_t *p_dec )
198	0	{
199	0	decoder_sys_t *p_sys = p_dec->p_sys;
200
201	0	packetizer_Flush( &p_sys->packetizer );
202	0	}
203
204		/*****************************************************************************
205		* Helpers:
206		*****************************************************************************/
207		static void PacketizeReset( void *p_private, bool b_flush )
208	0	{
209	0	decoder_t *p_dec = p_private;
210	0	decoder_sys_t *p_sys = p_dec->p_sys;
211
212	0	if( b_flush )
213	0	{
214	0	if( p_sys->p_frame )
215	0	block_ChainRelease( p_sys->p_frame );
216	0	p_sys->p_frame = NULL;
217	0	p_sys->pp_last = &p_sys->p_frame;
218	0	}
219
220	0	p_sys->i_interpolated_pts =
221	0	p_sys->i_interpolated_dts =
222	0	p_sys->i_last_ref_pts = VLC_TICK_INVALID;
223
224	0	p_sys->i_last_time_ref =
225	0	p_sys->i_time_ref =
226	0	p_sys->i_last_time =
227	0	p_sys->i_last_timeincr = 0;
228	0	}
229
230		static block_t PacketizeParse( void p_private, bool pb_ts_used, block_t p_block )
231	0	{
232	0	decoder_t *p_dec = p_private;
233	0	const vlc_tick_t i_dts = p_block->i_dts;
234	0	const vlc_tick_t i_pts = p_block->i_pts;
235
236	0	block_t *p_au = ParseMPEGBlock( p_dec, p_block );
237
238	0	*pb_ts_used = p_au && p_au->i_dts == i_dts && p_au->i_pts == i_pts;
239
240	0	return p_au;
241	0	}
242
243
244		static int PacketizeValidate( void p_private, block_t p_au )
245	0	{
246	0	decoder_t *p_dec = p_private;
247	0	decoder_sys_t *p_sys = p_dec->p_sys;
248
249		/* We've just started the stream, wait for the first PTS.
250		* We discard here so we can still get the sequence header. */
251	0	if( p_sys->i_interpolated_pts == VLC_TICK_INVALID &&
252	0	p_sys->i_interpolated_dts == VLC_TICK_INVALID )
253	0	{
254	0	msg_Dbg( p_dec, "need a starting pts/dts" );
255	0	return VLC_EGENERIC;
256	0	}
257
258		/* When starting the stream we can have the first frame with
259		* a null DTS (i_interpolated_pts is initialized to 0) */
260	0	if( p_au->i_dts == VLC_TICK_INVALID )
261	0	p_au->i_dts = p_au->i_pts;
262	0	return VLC_SUCCESS;
263	0	}
264
265		/*****************************************************************************
266		* ParseMPEGBlock: Re-assemble fragments into a block containing a picture
267		*****************************************************************************/
268		static block_t ParseMPEGBlock( decoder_t p_dec, block_t *p_frag )
269	0	{
270	0	decoder_sys_t *p_sys = p_dec->p_sys;
271	0	block_t *p_pic = NULL;
272
273	0	if( p_frag->i_buffer < 4 )
274	0	return p_frag;
275
276	0	const uint32_t i_startcode = GetDWBE( p_frag->p_buffer );
277	0	if( i_startcode == VISUAL_OBJECT_SEQUENCE_START_CODE \|\|
278	0	i_startcode == VISUAL_OBJECT_SEQUENCE_END_CODE \|\|
279	0	i_startcode == USER_DATA_START_CODE )
280	0	{ /* VOS and USERDATA */
281		#if 0
282		/* Remove VOS start/end code from the original stream */
283		block_Release( p_frag );
284		#else
285		/* Append the block for now since ts/ps muxers rely on VOL
286		* being present in the stream */
287	0	block_ChainLastAppend( &p_sys->pp_last, p_frag );
288	0	#endif
289	0	return NULL;
290	0	}
291	0	else if( i_startcode >= VIDEO_OBJECT_LAYER_START_CODE &&
292	0	i_startcode < RESERVED_START_CODE )
293	0	{
294		/* Copy the complete VOL */
295	0	if( (size_t)p_dec->fmt_out.i_extra != p_frag->i_buffer \|\|
296	0	( p_frag->i_buffer && memcmp(p_dec->fmt_out.p_extra,
297	0	p_frag->p_buffer, p_frag->i_buffer) ) )
298	0	{
299	0	void *p_realloc = realloc( p_dec->fmt_out.p_extra, p_frag->i_buffer );
300	0	if( p_realloc )
301	0	{
302	0	p_dec->fmt_out.p_extra = p_realloc;
303	0	p_dec->fmt_out.i_extra = p_frag->i_buffer;
304	0	memcpy( p_realloc, p_frag->p_buffer, p_frag->i_buffer );
305	0	}
306	0	}
307	0	ParseVOL( p_dec, &p_dec->fmt_out,
308	0	p_dec->fmt_out.p_extra, p_dec->fmt_out.i_extra );
309
310		#if 0
311		/* Remove from the original stream */
312		block_Release( p_frag );
313		#else
314		/* Append the block for now since ts/ps muxers rely on VOL
315		* being present in the stream */
316	0	block_ChainLastAppend( &p_sys->pp_last, p_frag );
317	0	#endif
318	0	return NULL;
319	0	}
320	0	else
321	0	{
322	0	if( !p_dec->fmt_out.i_extra )
323	0	{
324	0	msg_Warn( p_dec, "waiting for VOL" );
325	0	block_Release( p_frag );
326	0	return NULL;
327	0	}
328
329		/* Append the block */
330	0	block_ChainLastAppend( &p_sys->pp_last, p_frag );
331	0	}
332
333	0	if( i_startcode == VISUAL_OBJECT_START_CODE )
334	0	{
335	0	ParseVO( p_dec, p_frag );
336	0	}
337	0	else
338	0	if( i_startcode == VOP_START_CODE &&
339	0	ParseVOP( p_dec, p_frag ) == VLC_SUCCESS )
340	0	{
341		/* We are dealing with a VOP */
342	0	p_pic = block_ChainGather( p_sys->p_frame );
343	0	p_pic->i_flags = p_sys->i_flags;
344	0	p_pic->i_pts = p_sys->i_interpolated_pts;
345	0	p_pic->i_dts = p_sys->i_interpolated_dts;
346
347		#if 0
348		msg_Err( p_dec, "output dts/pts (%"PRId64",%"PRId64")", p_pic->i_dts, p_pic->i_pts );
349		#endif
350		/* Reset context */
351	0	p_sys->p_frame = NULL;
352	0	p_sys->pp_last = &p_sys->p_frame;
353	0	}
354
355	0	return p_pic;
356	0	}
357
358		/* ParseVOL: */
359		static int ParseVOL( decoder_t p_dec, es_format_t fmt,
360		uint8_t *p_vol, int i_vol )
361	610	{
362	610	decoder_sys_t *p_sys = p_dec->p_sys;
363	610	int i_vo_ver_id, i_shape;
364	610	h26x_aspect_ratio_t ar;
365	610	bs_t s;
366
367	610	for( ;; )
368	46.9k	{
369	46.9k	if( i_vol <= 5 )
370	93	return VLC_EGENERIC;
371
372	46.8k	uint32_t i_startcode = GetDWBE( p_vol );
373	46.8k	if( i_startcode >= VIDEO_OBJECT_LAYER_START_CODE &&
374	34.3k	i_startcode < RESERVED_START_CODE )
375	517	break;
376
377	46.3k	p_vol++; i_vol--;
378	46.3k	}
379
380	517	bs_init( &s, &p_vol[4], i_vol - 4 );
381
382	517	bs_skip( &s, 1 ); /* random access */
383	517	bs_skip( &s, 8 ); /* vo_type */
384	517	if( bs_read1( &s ) )
385	415	{
386	415	i_vo_ver_id = bs_read( &s, 4 );
387	415	bs_skip( &s, 3 );
388	415	}
389	102	else
390	102	{
391	102	i_vo_ver_id = 1;
392	102	}
393	517	ar.aspect_ratio_idc = bs_read( &s, 4 ) & 0xf;
394	517	if( ar.aspect_ratio_idc == 0xf )
395	51	{
396	51	ar.aspect_ratio_idc = 0xff; // was only coded on 4 bits in MPEG4
397	51	ar.sar_width = bs_read( &s, 8 );
398	51	ar.sar_height = bs_read( &s, 8 );
399	51	}
400	517	if(!p_dec->fmt_in->video.i_sar_num \|\|
401	19	!p_dec->fmt_in->video.i_sar_den)
402	498	{
403	498	h26x_get_aspect_ratio(&ar,
404	498	&fmt->video.i_sar_num,
405	498	&fmt->video.i_sar_den);
406	498	}
407
408	517	if( bs_read1( &s ) )
409	318	{
410		/* vol control parameter */
411	318	bs_skip( &s, 2 ); /* chroma_format */
412	318	bs_skip( &s, 1 ); /* low_delay */
413
414	318	if( bs_read1( &s ) )
415	98	{
416	98	bs_skip( &s, 16 );
417	98	bs_skip( &s, 16 );
418	98	bs_skip( &s, 16 );
419	98	bs_skip( &s, 3 );
420	98	bs_skip( &s, 11 );
421	98	bs_skip( &s, 1 );
422	98	bs_skip( &s, 16 );
423	98	}
424	318	}
425		/* shape 0->RECT, 1->BIN, 2->BIN_ONLY, 3->GRAY */
426	517	i_shape = bs_read( &s, 2 );
427	517	if( i_shape == 3 && i_vo_ver_id != 1 )
428	32	{
429	32	bs_skip( &s, 4 );
430	32	}
431
432	517	if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */
433
434	311	p_sys->i_fps_num = bs_read( &s, 16 ); /* Time increment resolution*/
435	311	if( !p_sys->i_fps_num ) p_sys->i_fps_num = 1;
436
437	311	if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */
438
439	293	if( bs_read1( &s ) )
440	248	{
441	248	int i_time_increment_bits = vlc_log2( p_sys->i_fps_num - 1 ) + 1;
442
443	248	if( i_time_increment_bits < 1 ) i_time_increment_bits = 1;
444
445	248	p_sys->i_fps_den = bs_read( &s, i_time_increment_bits );
446	248	}
447	293	if( i_shape == 0 )
448	237	{
449	237	bs_skip( &s, 1 );
450	237	fmt->video.i_width = bs_read( &s, 13 );
451	237	bs_skip( &s, 1 );
452	237	fmt->video.i_height= bs_read( &s, 13 );
453	237	bs_skip( &s, 1 );
454	237	}
455
456	293	return VLC_SUCCESS;
457	311	}
458
459		static int ParseVO( decoder_t p_dec, block_t p_vo )
460	0	{
461	0	bs_t s;
462	0	bs_init( &s, &p_vo->p_buffer[4], p_vo->i_buffer - 4 );
463	0	if( bs_read1( &s ) )
464	0	bs_skip( &s, 7 );
465
466	0	const uint8_t visual_object_type = bs_read( &s, 4 );
467	0	if( visual_object_type == 1 /* video ID */ \|\|
468	0	visual_object_type == 2 /* still texture ID */ )
469	0	{
470	0	h26x_colour_description_t colour =
471	0	{
472	0	.colour_primaries = 1,
473	0	.transfer_characteristics = 1,
474	0	.matrix_coeffs = 1,
475	0	.full_range_flag = 0,
476	0	};
477	0	if( bs_read1( &s ) ) /* video_signal_type */
478	0	{
479	0	bs_skip( &s, 3 );
480	0	colour.full_range_flag = bs_read( &s, 1 );
481	0	if( bs_read( &s, 1 ) ) /* colour description */
482	0	{
483	0	colour.colour_primaries = bs_read( &s, 8 );
484	0	colour.transfer_characteristics = bs_read( &s, 8 );
485	0	colour.matrix_coeffs = bs_read( &s, 8 );
486	0	}
487	0	}
488
489	0	if( p_dec->fmt_in->video.primaries == COLOR_PRIMARIES_UNDEF )
490	0	{
491	0	h26x_get_colorimetry( &colour,
492	0	&p_dec->fmt_out.video.primaries,
493	0	&p_dec->fmt_out.video.transfer,
494	0	&p_dec->fmt_out.video.space,
495	0	&p_dec->fmt_out.video.color_range );
496	0	}
497	0	}
498
499	0	return VLC_SUCCESS;
500	0	}
501
502		static int ParseVOP( decoder_t p_dec, block_t p_vop )
503	0	{
504	0	decoder_sys_t *p_sys = p_dec->p_sys;
505	0	int64_t i_time_increment, i_time_ref;
506	0	int i_modulo_time_base = 0, i_time_increment_bits;
507	0	bs_t s;
508
509	0	bs_init( &s, &p_vop->p_buffer[4], p_vop->i_buffer - 4 );
510
511	0	switch( bs_read( &s, 2 ) )
512	0	{
513	0	case 0:
514	0	p_sys->i_flags = BLOCK_FLAG_TYPE_I;
515	0	break;
516	0	case 1:
517	0	p_sys->i_flags = BLOCK_FLAG_TYPE_P;
518	0	break;
519	0	case 2:
520	0	p_sys->i_flags = BLOCK_FLAG_TYPE_B;
521	0	p_sys->b_frame = true;
522	0	break;
523	0	case 3: /* gni ? */
524	0	p_sys->i_flags = BLOCK_FLAG_TYPE_PB;
525	0	break;
526	0	}
527
528	0	while( bs_read( &s, 1 ) ) i_modulo_time_base++;
529	0	if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */
530
531		/* VOP time increment */
532	0	i_time_increment_bits = vlc_log2(p_sys->i_fps_num - 1) + 1;
533	0	if( i_time_increment_bits < 1 ) i_time_increment_bits = 1;
534	0	i_time_increment = bs_read( &s, i_time_increment_bits );
535
536		/* Interpolate PTS/DTS */
537	0	if( !(p_sys->i_flags & BLOCK_FLAG_TYPE_B) )
538	0	{
539	0	p_sys->i_last_time_ref = p_sys->i_time_ref;
540	0	p_sys->i_time_ref +=
541	0	(i_modulo_time_base * p_sys->i_fps_num);
542	0	i_time_ref = p_sys->i_time_ref;
543	0	}
544	0	else
545	0	{
546	0	i_time_ref = p_sys->i_last_time_ref +
547	0	(i_modulo_time_base * p_sys->i_fps_num);
548	0	}
549
550	0	int64_t i_time_diff = (i_time_ref + i_time_increment) - (p_sys->i_last_time + p_sys->i_last_timeincr);
551	0	if( p_sys->i_fps_num && i_modulo_time_base == 0 && i_time_diff < 0 && -i_time_diff > p_sys->i_fps_num )
552	0	{
553	0	msg_Warn(p_dec, "missing modulo_time_base update");
554	0	i_modulo_time_base += -i_time_diff / p_sys->i_fps_num;
555	0	p_sys->i_time_ref += (i_modulo_time_base * p_sys->i_fps_num);
556	0	p_sys->i_time_ref += p_sys->i_last_timeincr % p_sys->i_fps_num;
557	0	i_time_ref = p_sys->i_time_ref;
558	0	}
559
560	0	if( p_sys->i_fps_num < 5 && /* Work-around buggy streams */
561	0	p_dec->fmt_in->video.i_frame_rate > 0 &&
562	0	p_dec->fmt_in->video.i_frame_rate_base > 0 )
563	0	{
564	0	p_sys->i_interpolated_pts += vlc_tick_from_samples(
565	0	p_dec->fmt_in->video.i_frame_rate_base,
566	0	p_dec->fmt_in->video.i_frame_rate);
567	0	}
568	0	else if( p_sys->i_fps_num )
569	0	{
570	0	i_time_diff = (i_time_ref + i_time_increment) - (p_sys->i_last_time + p_sys->i_last_timeincr);
571	0	p_sys->i_interpolated_pts += vlc_tick_from_samples( i_time_diff, p_sys->i_fps_num );
572	0	}
573
574		#if 0
575		msg_Err( p_dec, "interp dts/pts (%"PRId64",%"PRId64"), dts/pts (%"PRId64",%"PRId64") %"PRId64" mod %d inc %"PRId64,
576		p_sys->i_interpolated_dts, p_sys->i_interpolated_pts,
577		p_vop->i_dts, p_vop->i_pts, p_sys->i_time_ref, i_modulo_time_base, i_time_increment );
578		#endif
579
580	0	p_sys->i_last_time = i_time_ref;
581	0	p_sys->i_last_timeincr = i_time_increment;
582
583		/* Correct interpolated dts when we receive a new pts/dts */
584	0	if( p_vop->i_pts != VLC_TICK_INVALID )
585	0	p_sys->i_interpolated_pts = p_vop->i_pts;
586	0	if( p_vop->i_dts != VLC_TICK_INVALID )
587	0	p_sys->i_interpolated_dts = p_vop->i_dts;
588
589	0	if( (p_sys->i_flags & BLOCK_FLAG_TYPE_B) \|\| !p_sys->b_frame )
590	0	{
591		/* Trivial case (DTS == PTS) */
592
593	0	p_sys->i_interpolated_dts = p_sys->i_interpolated_pts;
594
595	0	if( p_vop->i_pts != VLC_TICK_INVALID )
596	0	p_sys->i_interpolated_dts = p_vop->i_pts;
597	0	if( p_vop->i_dts != VLC_TICK_INVALID )
598	0	p_sys->i_interpolated_dts = p_vop->i_dts;
599
600	0	p_sys->i_interpolated_pts = p_sys->i_interpolated_dts;
601	0	}
602	0	else
603	0	{
604	0	if( p_sys->i_last_ref_pts != VLC_TICK_INVALID )
605	0	p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;
606
607	0	p_sys->i_last_ref_pts = p_sys->i_interpolated_pts;
608	0	}
609
610	0	return VLC_SUCCESS;
611	0	}
612
613		/* look at libavutil av_log2 ;) */
614		static int vlc_log2( unsigned int v )
615	248	{
616	248	int n = 0;
617	248	static const int vlc_log2_table[16] =
618	248	{
619	248	0,0,1,1,2,2,2,2, 3,3,3,3,3,3,3,3
620	248	};
621
622	248	if( v&0xffff0000 )
623	0	{
624	0	v >>= 16;
625	0	n += 16;
626	0	}
627	248	if( v&0xff00 )
628	245	{
629	245	v >>= 8;
630	245	n += 8;
631	245	}
632	248	if( v&0xf0 )
633	244	{
634	244	v >>= 4;
635	244	n += 4;
636	244	}
637	248	n += vlc_log2_table[v];
638
639	248	return n;
640	248	}