/*****************************************************************************

 * mpg123.c: MPEG-1 & 2 audio layer I, II, III + MPEG 2.5 decoder

 *****************************************************************************

 * Copyright (C) 2001-2016 VLC authors and VideoLAN

 *

 * Authors: Ludovic Fauvet <etix@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 <assert.h>

#include <mpg123.h>

#include <vlc_common.h>

#include <vlc_plugin.h>

#include <vlc_aout.h>

#include <vlc_block.h>

#include <vlc_codec.h>

/*****************************************************************************

 * Local prototypes

 *****************************************************************************/

static int      OpenDecoder( vlc_object_t * );

static void     CloseDecoder( vlc_object_t * );

static unsigned int mpg123_refcount = 0;

static vlc_mutex_t mpg123_mutex = VLC_STATIC_MUTEX;

/*****************************************************************************

 * Local structures

 *****************************************************************************/

typedef struct

{

    mpg123_handle * p_handle;

    date_t          end_date;

    block_t       * p_out;

    bool            b_opened;

} decoder_sys_t;

/*****************************************************************************

 * Module descriptor

 *****************************************************************************/

vlc_module_begin ()

    set_subcategory( SUBCAT_INPUT_ACODEC )

    set_description( N_("MPEG audio decoder using mpg123") )

    set_capability( "audio decoder", 100 )

    set_shortname( "mpg123" )

    set_callbacks( OpenDecoder, CloseDecoder )

vlc_module_end ()

/*****************************************************************************

 * MPG123Open

 *****************************************************************************/

static int MPG123Open( decoder_t *p_dec )

{

    decoder_sys_t *p_sys = p_dec->p_sys;

    /* Create our mpg123 handle */

    if( ( p_sys->p_handle = mpg123_new( NULL, NULL ) ) == NULL )

    {

        msg_Err( p_dec, "mpg123 error: can't create handle" );

        return VLC_EGENERIC;

    }

    /* Open a new bitstream */

    if( mpg123_open_feed( p_sys->p_handle ) != MPG123_OK )

    {

        msg_Err( p_dec, "mpg123 error: can't open feed" );

        mpg123_delete( p_sys->p_handle );

        return VLC_EGENERIC;

    }

    /* Disable resync stream after error */

    mpg123_param( p_sys->p_handle, MPG123_ADD_FLAGS, MPG123_NO_RESYNC, 0 );

    /* Setup output format */

    mpg123_format_none( p_sys->p_handle );

    int i_ret = MPG123_OK;

    if( p_dec->fmt_in->audio.i_rate != 0 )

    {

        i_ret =  mpg123_format( p_sys->p_handle, p_dec->fmt_in->audio.i_rate,

                                MPG123_MONO | MPG123_STEREO,

                                MPG123_ENC_FLOAT_32 );

    }

    else

    {

        /* The rate from the input is unknown. Tell mpg123 to accept all rates

         * to avoid conversion on their side */

        static const long mp3_rates[] = {

            8000, 11025, 12000, 16000, 22050, 24000, 32000, 44100, 48000,

        };

        for( size_t i = 0; i < ARRAY_SIZE(mp3_rates) && i_ret == MPG123_OK; ++i )

        {

            i_ret =  mpg123_format( p_sys->p_handle, mp3_rates[i],

                                    MPG123_MONO | MPG123_STEREO,

                                    MPG123_ENC_FLOAT_32 );

        }

    }

    if( i_ret != MPG123_OK )

    {

        msg_Err( p_dec, "mpg123 error: %s",

                 mpg123_strerror( p_sys->p_handle ) );

        mpg123_close( p_sys->p_handle );

        mpg123_delete( p_sys->p_handle );

        return VLC_EGENERIC;

    }

    p_sys->b_opened = true;

    return VLC_SUCCESS;

}

/*****************************************************************************

 * Flush:

 *****************************************************************************/

static void Flush( decoder_t *p_dec )

{

    decoder_sys_t *p_sys = p_dec->p_sys;

    date_Set( &p_sys->end_date, VLC_TICK_INVALID );

    mpg123_close( p_sys->p_handle );

    mpg123_delete( p_sys->p_handle );

    p_sys->b_opened = false;

    MPG123Open( p_dec );

}

static int UpdateAudioFormat( decoder_t *p_dec )

{

    int i_err;

    decoder_sys_t *p_sys = p_dec->p_sys;

    struct mpg123_frameinfo frame_info;

    /* Get details about the stream */

    i_err = mpg123_info( p_sys->p_handle, &frame_info );

    if( i_err != MPG123_OK )

    {

        msg_Err( p_dec, "mpg123_info failed: %s",

                 mpg123_plain_strerror( i_err ) );

        return VLC_EGENERIC;

    }

    p_dec->fmt_out.i_bitrate = frame_info.bitrate * 1000;

    switch( frame_info.mode )

    {

        case MPG123_M_DUAL:

            p_dec->fmt_out.audio.i_chan_mode = AOUT_CHANMODE_DUALMONO;

            /* fall through */

        case MPG123_M_STEREO:

        case MPG123_M_JOINT:

            p_dec->fmt_out.audio.i_physical_channels =

                AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;

            break;

        case MPG123_M_MONO:

            p_dec->fmt_out.audio.i_physical_channels = AOUT_CHAN_CENTER;

            break;

        default:

            return VLC_EGENERIC;

    }

    aout_FormatPrepare( &p_dec->fmt_out.audio );

    /* Date management */

    if( p_dec->fmt_out.audio.i_rate != (unsigned int)frame_info.rate )

    {

        p_dec->fmt_out.audio.i_rate = (unsigned int)frame_info.rate;

        date_Init( &p_sys->end_date, p_dec->fmt_out.audio.i_rate, 1 );

    }

    return decoder_UpdateAudioFormat( p_dec );

}

/****************************************************************************

 * DecodeBlock: the whole thing

 ****************************************************************************/

static int DecodeBlock( decoder_t *p_dec, block_t *p_block )

{

    int i_err;

    decoder_sys_t *p_sys = p_dec->p_sys;

    vlc_tick_t i_pts = VLC_TICK_INVALID;

    if( !p_sys->b_opened )

    {

        if( p_block )

            block_Release( p_block );

        return VLCDEC_ECRITICAL;

    }

    /* Feed input block */

    if( p_block != NULL )

    {

        i_pts = p_block->i_pts != VLC_TICK_INVALID ? p_block->i_pts : p_block->i_dts;

        if( p_block->i_flags & (BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )

        {

            Flush( p_dec );

            if( p_block->i_flags & BLOCK_FLAG_CORRUPTED )

            {

                block_Release( p_block );

                return VLCDEC_SUCCESS;

            }

        }

        if( i_pts == VLC_TICK_INVALID &&

            date_Get( &p_sys->end_date ) == VLC_TICK_INVALID )

        {

            /* We've just started the stream, wait for the first PTS. */

            msg_Dbg( p_dec, "waiting for PTS" );

            block_Release( p_block );

            return VLCDEC_SUCCESS;

        }

        /* Feed mpg123 with raw data */

        i_err = mpg123_feed( p_sys->p_handle, p_block->p_buffer, p_block->i_buffer );

        block_Release( p_block );

        if( i_err != MPG123_OK )

        {

            msg_Err( p_dec, "mpg123_feed failed: %s",

                     mpg123_plain_strerror( i_err ) );

            return VLCDEC_SUCCESS;

        }

    }

    while( true )

    {

        /* Fetch a new output block (if possible) */

        if( !p_sys->p_out

            || p_sys->p_out->i_buffer != mpg123_outblock( p_sys->p_handle ) )

        {

            if( p_sys->p_out )

                block_Release( p_sys->p_out );

            /* Keep the output buffer for next calls in case it's not used (in case

             * of MPG123_NEED_MORE status) */

            p_sys->p_out = block_Alloc( mpg123_outblock( p_sys->p_handle ) );

            if( unlikely( !p_sys->p_out ) )

                return VLCDEC_SUCCESS;

        }

        /* Do the actual decoding now */

        size_t i_bytes = 0;

        /* Make mpg123 write directly into the VLC output buffer */

        i_err = mpg123_replace_buffer( p_sys->p_handle, p_sys->p_out->p_buffer,

                                       p_sys->p_out->i_buffer );

        if( i_err != MPG123_OK )

        {

            msg_Err( p_dec, "could not replace buffer: %s",

                     mpg123_plain_strerror( i_err ) );

            block_Release( p_sys->p_out );

            p_sys->p_out = NULL;

            break;

        }

        i_err = mpg123_decode_frame( p_sys->p_handle, NULL, NULL, &i_bytes );

        if( i_err != MPG123_OK && i_err != MPG123_NEED_MORE )

        {

            if( i_err == MPG123_NEW_FORMAT )

            {

                p_dec->fmt_out.audio.i_rate = 0;

            }

            else

            {

                msg_Err( p_dec, "mpg123_decode_frame error: %s",

                         mpg123_plain_strerror( i_err ) );

                date_Set( &p_sys->end_date, VLC_TICK_INVALID );

                break;

            }

        }

        if( i_bytes == 0 )

            break;

        if( p_dec->fmt_out.audio.i_rate == 0 )

        {

            if( UpdateAudioFormat( p_dec ) != VLC_SUCCESS )

            {

                date_Set( &p_sys->end_date, VLC_TICK_INVALID );

                break;

            }

        }

        block_t *p_out = p_sys->p_out;

        p_sys->p_out = NULL;

        if( date_Get( &p_sys->end_date ) == VLC_TICK_INVALID )

        {

            if( i_pts != VLC_TICK_INVALID )

            {

                date_Set( &p_sys->end_date, i_pts );

            }

            else if( p_out ) /* we need a valid date and that's not guaranteed on flush/error */

            {

                block_Release( p_out );

                break;

            }

        }

        if( p_out )

        {

            assert( p_dec->fmt_out.audio.i_rate != 0 );

            assert( p_out->i_buffer >= i_bytes );

            p_out->i_buffer = i_bytes;

            p_out->i_nb_samples = p_out->i_buffer * p_dec->fmt_out.audio.i_frame_length

                                / p_dec->fmt_out.audio.i_bytes_per_frame;

            /* Configure the buffer */

            p_out->i_dts = p_out->i_pts = date_Get( &p_sys->end_date );

            p_out->i_length = date_Increment( &p_sys->end_date, p_out->i_nb_samples )

                            - p_out->i_pts;

            decoder_QueueAudio( p_dec, p_out );

        }

    }

    return VLCDEC_SUCCESS;

}

/*****************************************************************************

 * InitMPG123 : initialize the mpg123 library (reentrant)

 *****************************************************************************/

static int InitMPG123( void )

{

    int i_ret;

    vlc_mutex_lock( &mpg123_mutex );

    if( mpg123_refcount > 0 )

    {

        mpg123_refcount++;

        vlc_mutex_unlock( &mpg123_mutex );

        return MPG123_OK;

    }

    if( ( i_ret = mpg123_init() ) == MPG123_OK )

        mpg123_refcount++;

    vlc_mutex_unlock( &mpg123_mutex );

    return i_ret;

}

/*****************************************************************************

 * ExitMPG123 : close down the mpg123 library (reentrant)

 *****************************************************************************/

static void ExitMPG123( void )

{

    vlc_mutex_lock( &mpg123_mutex );

    mpg123_refcount--;

    if( mpg123_refcount == 0 )

        mpg123_exit();

    vlc_mutex_unlock( &mpg123_mutex );

}

/*****************************************************************************

 * OpenDecoder :

 *****************************************************************************/

static int OpenDecoder( 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_MPGA &&

        p_dec->fmt_in->i_codec != VLC_CODEC_MP2 &&

        p_dec->fmt_in->i_codec != VLC_CODEC_MP3 )

        return VLC_EGENERIC;

    /* Initialize libmpg123 */

    if( InitMPG123() != MPG123_OK )

        return VLC_EGENERIC;

    /* Allocate the memory needed to store the module's structure */

    p_sys = p_dec->p_sys = malloc( sizeof(decoder_sys_t) );

    if( p_sys == NULL )

        return VLC_ENOMEM;

    p_sys->p_out = NULL;

    date_Set( &p_sys->end_date, VLC_TICK_INVALID );

    if( MPG123Open( p_dec ) )

        goto error;

    p_dec->fmt_out.i_codec = VLC_CODEC_FL32;

    p_dec->fmt_out.audio.i_rate = 0; /* So end_date gets initialized */

    p_dec->fmt_out.audio.i_format = p_dec->fmt_out.i_codec;

    p_dec->pf_decode = DecodeBlock;

    p_dec->pf_flush  = Flush;

    msg_Dbg( p_this, "%4.4s->%4.4s, bits per sample: %i",

             (char *)&p_dec->fmt_in->i_codec,

             (char *)&p_dec->fmt_out.i_codec,

             aout_BitsPerSample( p_dec->fmt_out.i_codec ) );

    return VLC_SUCCESS;

error:

    ExitMPG123();

    free( p_sys );

    return VLC_EGENERIC;

}

/*****************************************************************************

 * CloseDecoder : deallocate data structures

 *****************************************************************************/

static void CloseDecoder( vlc_object_t *p_this )

{

    decoder_t *p_dec = (decoder_t *)p_this;

    decoder_sys_t *p_sys = p_dec->p_sys;

    mpg123_close( p_sys->p_handle );

    mpg123_delete( p_sys->p_handle );

    ExitMPG123();

    if( p_sys->p_out )

        block_Release( p_sys->p_out );

    free( p_sys );

}