/src/ffmpeg/libavformat/rtpdec_rfc4175.c

Source
/*
 * RTP Depacketization of RAW video (TR-03)
 * Copyright (c) 2016 Savoir-faire Linux, Inc
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg 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.
 *
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/* Development sponsored by CBC/Radio-Canada */

#include "avio_internal.h"
#include "rtpdec_formats.h"
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/imgutils.h"
#include "libavutil/mem.h"
#include "libavutil/pixdesc.h"
#include "libavutil/parseutils.h"

struct PayloadContext {
    char *sampling;
    AVRational framerate;
    int depth;
    int width;
    int height;
    int interlaced;
    int field;

    uint8_t *frame;
    unsigned int frame_size;
    unsigned int pgroup; /* size of the pixel group in bytes */
    unsigned int xinc;

    uint32_t timestamp;
};

static int rfc4175_parse_format(AVStream *stream, PayloadContext *data)
{
    enum AVPixelFormat pixfmt;
    int tag;
    const AVPixFmtDescriptor *desc;

    if (!strncmp(data->sampling, "YCbCr-4:2:2", 11)) {
        tag = MKTAG('U', 'Y', 'V', 'Y');
        data->xinc = 2;

        if (data->depth == 8) {
            data->pgroup = 4;
            pixfmt = AV_PIX_FMT_UYVY422;
            stream->codecpar->codec_id = AV_CODEC_ID_RAWVIDEO;
        } else if (data->depth == 10) {
            data->pgroup = 5;
            pixfmt = AV_PIX_FMT_YUV422P10;
            stream->codecpar->codec_id = AV_CODEC_ID_BITPACKED;
        } else {
            return AVERROR_INVALIDDATA;
        }
    } else if (!strncmp(data->sampling, "YCbCr-4:2:0", 11)) {
        tag = MKTAG('I', '4', '2', '0');
        data->xinc = 4;

        if (data->depth == 8) {
            data->pgroup = 6;
            pixfmt = AV_PIX_FMT_YUV420P;
            stream->codecpar->codec_id = AV_CODEC_ID_RAWVIDEO;
        } else {
            return AVERROR_INVALIDDATA;
        }
    } else if (!strncmp(data->sampling, "RGB", 3)) {
        tag = MKTAG('R', 'G', 'B', 24);
        if (data->depth == 8) {
            data->xinc = 1;
            data->pgroup = 3;
            pixfmt = AV_PIX_FMT_RGB24;
            stream->codecpar->codec_id = AV_CODEC_ID_RAWVIDEO;
        } else {
            return AVERROR_INVALIDDATA;
        }
    } else if (!strncmp(data->sampling, "BGR", 3)) {
        tag = MKTAG('B', 'G', 'R', 24);
        if (data->depth == 8) {
            data->xinc = 1;
            data->pgroup = 3;
            pixfmt = AV_PIX_FMT_BGR24;
            stream->codecpar->codec_id = AV_CODEC_ID_RAWVIDEO;
        } else {
            return AVERROR_INVALIDDATA;
        }
    } else {
        return AVERROR_INVALIDDATA;
    }

    desc = av_pix_fmt_desc_get(pixfmt);
    stream->codecpar->format = pixfmt;
    stream->codecpar->codec_tag = tag;
    stream->codecpar->bits_per_coded_sample = av_get_bits_per_pixel(desc);
    data->frame_size = data->width * data->height * data->pgroup / data->xinc;

    if (data->interlaced)
        stream->codecpar->field_order = AV_FIELD_TT;
    else
        stream->codecpar->field_order = AV_FIELD_PROGRESSIVE;

    if (data->framerate.den > 0) {
        stream->avg_frame_rate = data->framerate;
        stream->codecpar->bit_rate = data->frame_size * av_q2d(data->framerate) * 8;
    }

    return 0;
}

static int rfc4175_parse_fmtp(AVFormatContext *s, AVStream *stream,
                              PayloadContext *data, const char *attr,
                              const char *value)
{
    if (!strncmp(attr, "width", 5))
        data->width = atoi(value);
    else if (!strncmp(attr, "height", 6))
        data->height = atoi(value);
    else if (data->sampling == NULL && !strncmp(attr, "sampling", 8))
        data->sampling = av_strdup(value);
    else if (!strncmp(attr, "depth", 5))
        data->depth = atoi(value);
    else if (!strncmp(attr, "interlace", 9))
        data->interlaced = 1;
    else if (!strncmp(attr, "exactframerate", 14)) {
        if (av_parse_video_rate(&data->framerate, value) < 0)
            return AVERROR(EINVAL);
    } else if (!strncmp(attr, "TCS", 3)) {
        if (!strncmp(value, "SDR", 3))
            stream->codecpar->color_trc = AVCOL_TRC_BT709;
        else if (!strncmp(value, "PQ", 2))
            stream->codecpar->color_trc = AVCOL_TRC_SMPTE2084;
        else if (!strncmp(value, "HLG", 3))
            stream->codecpar->color_trc = AVCOL_TRC_ARIB_STD_B67;
        else if (!strncmp(value, "LINEAR", 6))
            stream->codecpar->color_trc = AVCOL_TRC_LINEAR;
        else if (!strncmp(value, "ST428-1", 7))
            stream->codecpar->color_trc = AVCOL_TRC_SMPTEST428_1;
        else
            stream->codecpar->color_trc = AVCOL_TRC_UNSPECIFIED;
    } else if (!strncmp(attr, "colorimetry", 11)) {
        if (!strncmp(value, "BT601", 5)) {
            stream->codecpar->color_primaries = AVCOL_PRI_BT470BG;
            stream->codecpar->color_space     = AVCOL_SPC_BT470BG;
        } else if (!strncmp(value, "BT709", 5)) {
            stream->codecpar->color_primaries = AVCOL_PRI_BT709;
            stream->codecpar->color_space     = AVCOL_SPC_BT709;
        } else if (!strncmp(value, "BT2020", 6)) {
            stream->codecpar->color_primaries = AVCOL_PRI_BT2020;
            stream->codecpar->color_space     = AVCOL_SPC_BT2020_NCL;
        }
    } else if (!strncmp(attr, "RANGE", 5)) {
        if (!strncmp(value, "NARROW", 6))
            stream->codecpar->color_range = AVCOL_RANGE_MPEG;
        else if (!strncmp(value, "FULL", 4))
            stream->codecpar->color_range = AVCOL_RANGE_JPEG;
    }

    return 0;
}

static int rfc4175_parse_sdp_line(AVFormatContext *s, int st_index,
                                  PayloadContext *data_arg, const char *line)
{
    const char *p;

    if (st_index < 0)
        return 0;

    av_assert0(!data_arg->sampling);

    if (av_strstart(line, "fmtp:", &p)) {
        AVStream *stream = s->streams[st_index];
        PayloadContext data0 = *data_arg, *data = &data0;
        int ret = ff_parse_fmtp(s, stream, data, p, rfc4175_parse_fmtp);

        if (!data->sampling || !data->depth || !data->width || !data->height)
            ret =  AVERROR(EINVAL);

        if (ret < 0)
            goto fail;

        ret = av_image_check_size(data->width, data->height, 0, s);
        if (ret < 0)
            goto fail;

        stream->codecpar->width = data->width;
        stream->codecpar->height = data->height;

        ret = rfc4175_parse_format(stream, data);
        av_freep(&data->sampling);
        if (ret >= 0)
            *data_arg = *data;
fail:
        av_freep(&data->sampling);
        return ret;
    }

    return 0;
}

static int rfc4175_finalize_packet(PayloadContext *data, AVPacket *pkt,
                                   int stream_index)
{
    int ret = AVERROR(EAGAIN);

    pkt->stream_index = stream_index;
    if (!data->interlaced || data->field) {
        ret = av_packet_from_data(pkt, data->frame, data->frame_size);
        if (ret < 0) {
            av_freep(&data->frame);
        }
        data->frame = NULL;
    }

    data->field = 0;

    return ret;
}

static int rfc4175_handle_packet(AVFormatContext *ctx, PayloadContext *data,
                                 AVStream *st, AVPacket *pkt, uint32_t *timestamp,
                                 const uint8_t * buf, int len,
                                 uint16_t seq, int flags)
{
    int length, line, offset, cont, field;
    const uint8_t *headers, *payload;
    int payload_len;
    int missed_last_packet = 0;

    uint8_t *dest;

    if (!buf) {
        *timestamp = data->timestamp;
        return rfc4175_finalize_packet(data, pkt, st->index);
    }

    headers = buf + 2; /* skip extended seqnum */
    payload = buf + 2;
    payload_len = len - 2;

    if (*timestamp != data->timestamp) {
        if (data->frame && (!data->interlaced || data->field)) {
            /*
             * if we're here, it means that we missed the cue to return
             * the previous AVPacket, that cue being the RTP_FLAG_MARKER
             * in the last packet of either the previous frame (progressive)
             * or the previous second field (interlace). Let's finalize the
             * previous frame (or pair of fields) anyway by filling the AVPacket.
             */
            av_log(ctx, AV_LOG_ERROR, "Missed previous RTP Marker\n");
            missed_last_packet = rfc4175_finalize_packet(data, pkt, st->index) >= 0;
        }

        if (!data->frame)
            data->frame = av_mallocz(data->frame_size + AV_INPUT_BUFFER_PADDING_SIZE);

        if (missed_last_packet)
            FFSWAP(uint32_t, data->timestamp, *timestamp);
        else
            data->timestamp = *timestamp;

        if (!data->frame) {
            av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");
            return missed_last_packet ? 0 : AVERROR(ENOMEM);
        }
    }

    /*
     * looks for the 'Continuation bit' in scan lines' headers
     * to find where data start
     */
    do {
        if (payload_len < 6)
            goto invalid;

        cont = payload[4] & 0x80;
        payload += 6;
        payload_len -= 6;
    } while (cont);

    /* and now iterate over every scan lines */
    do {
        int copy_offset;

        if (payload_len < data->pgroup)
            goto invalid;

        length = (headers[0] << 8) | headers[1];
        field = (headers[2] & 0x80) >> 7;
        line = ((headers[2] & 0x7f) << 8) | headers[3];
        offset = ((headers[4] & 0x7f) << 8) | headers[5];
        cont = headers[4] & 0x80;
        headers += 6;
        data->field = field;

        if (!data->pgroup || length % data->pgroup)
            goto invalid;

        if (length > payload_len)
            length = payload_len;

        if (data->interlaced)
            line = 2 * line + field;

        if (line >= data->height)
            goto invalid;

        /* prevent ill-formed packets to write after buffer's end */
        copy_offset = (line * data->width + offset) * data->pgroup / data->xinc;
        if (copy_offset + length > data->frame_size || !data->frame)
            goto invalid;

        dest = data->frame + copy_offset;
        memcpy(dest, payload, length);

        payload += length;
        payload_len -= length;
    } while (cont);

    if (missed_last_packet) {
        return !!(flags & RTP_FLAG_MARKER);
    } else if ((flags & RTP_FLAG_MARKER)) {
        return rfc4175_finalize_packet(data, pkt, st->index);
    }

    return AVERROR(EAGAIN);

invalid:
    return missed_last_packet ? 0 : AVERROR_INVALIDDATA;
}

static void rfc4175_close_context(PayloadContext *data)
{
    av_freep(&data->frame);
}

const RTPDynamicProtocolHandler ff_rfc4175_rtp_handler = {
    .enc_name           = "raw",
    .codec_type         = AVMEDIA_TYPE_VIDEO,
    .codec_id           = AV_CODEC_ID_NONE,
    .priv_data_size     = sizeof(PayloadContext),
    .parse_sdp_a_line   = rfc4175_parse_sdp_line,
    .parse_packet       = rfc4175_handle_packet,
    .close              = rfc4175_close_context,
};

Coverage Report

Created: 2026-10-28 08:13

Line	Count	Source
1		/*
2		* RTP Depacketization of RAW video (TR-03)
3		* Copyright (c) 2016 Savoir-faire Linux, Inc
4		*
5		* This file is part of FFmpeg.
6		*
7		* FFmpeg is free software; you can redistribute it and/or
8		* modify it under the terms of the GNU Lesser General Public
9		* License as published by the Free Software Foundation; either
10		* version 2.1 of the License, or (at your option) any later version.
11		*
12		* FFmpeg is distributed in the hope that it will be useful,
13		* but WITHOUT ANY WARRANTY; without even the implied warranty of
14		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15		* Lesser General Public License for more details.
16		*
17		* You should have received a copy of the GNU Lesser General Public
18		* License along with FFmpeg; if not, write to the Free Software
19		* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20		*/
21
22		/* Development sponsored by CBC/Radio-Canada */
23
24		#include "avio_internal.h"
25		#include "rtpdec_formats.h"
26		#include "libavutil/avassert.h"
27		#include "libavutil/avstring.h"
28		#include "libavutil/imgutils.h"
29		#include "libavutil/mem.h"
30		#include "libavutil/pixdesc.h"
31		#include "libavutil/parseutils.h"
32
33		struct PayloadContext {
34		char *sampling;
35		AVRational framerate;
36		int depth;
37		int width;
38		int height;
39		int interlaced;
40		int field;
41
42		uint8_t *frame;
43		unsigned int frame_size;
44		unsigned int pgroup; /* size of the pixel group in bytes */
45		unsigned int xinc;
46
47		uint32_t timestamp;
48		};
49
50		static int rfc4175_parse_format(AVStream stream, PayloadContext data)
51	0	{
52	0	enum AVPixelFormat pixfmt;
53	0	int tag;
54	0	const AVPixFmtDescriptor *desc;
55
56	0	if (!strncmp(data->sampling, "YCbCr-4:2:2", 11)) {
57	0	tag = MKTAG('U', 'Y', 'V', 'Y');
58	0	data->xinc = 2;
59
60	0	if (data->depth == 8) {
61	0	data->pgroup = 4;
62	0	pixfmt = AV_PIX_FMT_UYVY422;
63	0	stream->codecpar->codec_id = AV_CODEC_ID_RAWVIDEO;
64	0	} else if (data->depth == 10) {
65	0	data->pgroup = 5;
66	0	pixfmt = AV_PIX_FMT_YUV422P10;
67	0	stream->codecpar->codec_id = AV_CODEC_ID_BITPACKED;
68	0	} else {
69	0	return AVERROR_INVALIDDATA;
70	0	}
71	0	} else if (!strncmp(data->sampling, "YCbCr-4:2:0", 11)) {
72	0	tag = MKTAG('I', '4', '2', '0');
73	0	data->xinc = 4;
74
75	0	if (data->depth == 8) {
76	0	data->pgroup = 6;
77	0	pixfmt = AV_PIX_FMT_YUV420P;
78	0	stream->codecpar->codec_id = AV_CODEC_ID_RAWVIDEO;
79	0	} else {
80	0	return AVERROR_INVALIDDATA;
81	0	}
82	0	} else if (!strncmp(data->sampling, "RGB", 3)) {
83	0	tag = MKTAG('R', 'G', 'B', 24);
84	0	if (data->depth == 8) {
85	0	data->xinc = 1;
86	0	data->pgroup = 3;
87	0	pixfmt = AV_PIX_FMT_RGB24;
88	0	stream->codecpar->codec_id = AV_CODEC_ID_RAWVIDEO;
89	0	} else {
90	0	return AVERROR_INVALIDDATA;
91	0	}
92	0	} else if (!strncmp(data->sampling, "BGR", 3)) {
93	0	tag = MKTAG('B', 'G', 'R', 24);
94	0	if (data->depth == 8) {
95	0	data->xinc = 1;
96	0	data->pgroup = 3;
97	0	pixfmt = AV_PIX_FMT_BGR24;
98	0	stream->codecpar->codec_id = AV_CODEC_ID_RAWVIDEO;
99	0	} else {
100	0	return AVERROR_INVALIDDATA;
101	0	}
102	0	} else {
103	0	return AVERROR_INVALIDDATA;
104	0	}
105
106	0	desc = av_pix_fmt_desc_get(pixfmt);
107	0	stream->codecpar->format = pixfmt;
108	0	stream->codecpar->codec_tag = tag;
109	0	stream->codecpar->bits_per_coded_sample = av_get_bits_per_pixel(desc);
110	0	data->frame_size = data->width * data->height * data->pgroup / data->xinc;
111
112	0	if (data->interlaced)
113	0	stream->codecpar->field_order = AV_FIELD_TT;
114	0	else
115	0	stream->codecpar->field_order = AV_FIELD_PROGRESSIVE;
116
117	0	if (data->framerate.den > 0) {
118	0	stream->avg_frame_rate = data->framerate;
119	0	stream->codecpar->bit_rate = data->frame_size * av_q2d(data->framerate) * 8;
120	0	}
121
122	0	return 0;
123	0	}
124
125		static int rfc4175_parse_fmtp(AVFormatContext s, AVStream stream,
126		PayloadContext data, const char attr,
127		const char *value)
128	0	{
129	0	if (!strncmp(attr, "width", 5))
130	0	data->width = atoi(value);
131	0	else if (!strncmp(attr, "height", 6))
132	0	data->height = atoi(value);
133	0	else if (data->sampling == NULL && !strncmp(attr, "sampling", 8))
134	0	data->sampling = av_strdup(value);
135	0	else if (!strncmp(attr, "depth", 5))
136	0	data->depth = atoi(value);
137	0	else if (!strncmp(attr, "interlace", 9))
138	0	data->interlaced = 1;
139	0	else if (!strncmp(attr, "exactframerate", 14)) {
140	0	if (av_parse_video_rate(&data->framerate, value) < 0)
141	0	return AVERROR(EINVAL);
142	0	} else if (!strncmp(attr, "TCS", 3)) {
143	0	if (!strncmp(value, "SDR", 3))
144	0	stream->codecpar->color_trc = AVCOL_TRC_BT709;
145	0	else if (!strncmp(value, "PQ", 2))
146	0	stream->codecpar->color_trc = AVCOL_TRC_SMPTE2084;
147	0	else if (!strncmp(value, "HLG", 3))
148	0	stream->codecpar->color_trc = AVCOL_TRC_ARIB_STD_B67;
149	0	else if (!strncmp(value, "LINEAR", 6))
150	0	stream->codecpar->color_trc = AVCOL_TRC_LINEAR;
151	0	else if (!strncmp(value, "ST428-1", 7))
152	0	stream->codecpar->color_trc = AVCOL_TRC_SMPTEST428_1;
153	0	else
154	0	stream->codecpar->color_trc = AVCOL_TRC_UNSPECIFIED;
155	0	} else if (!strncmp(attr, "colorimetry", 11)) {
156	0	if (!strncmp(value, "BT601", 5)) {
157	0	stream->codecpar->color_primaries = AVCOL_PRI_BT470BG;
158	0	stream->codecpar->color_space = AVCOL_SPC_BT470BG;
159	0	} else if (!strncmp(value, "BT709", 5)) {
160	0	stream->codecpar->color_primaries = AVCOL_PRI_BT709;
161	0	stream->codecpar->color_space = AVCOL_SPC_BT709;
162	0	} else if (!strncmp(value, "BT2020", 6)) {
163	0	stream->codecpar->color_primaries = AVCOL_PRI_BT2020;
164	0	stream->codecpar->color_space = AVCOL_SPC_BT2020_NCL;
165	0	}
166	0	} else if (!strncmp(attr, "RANGE", 5)) {
167	0	if (!strncmp(value, "NARROW", 6))
168	0	stream->codecpar->color_range = AVCOL_RANGE_MPEG;
169	0	else if (!strncmp(value, "FULL", 4))
170	0	stream->codecpar->color_range = AVCOL_RANGE_JPEG;
171	0	}
172
173	0	return 0;
174	0	}
175
176		static int rfc4175_parse_sdp_line(AVFormatContext *s, int st_index,
177		PayloadContext data_arg, const char line)
178	0	{
179	0	const char *p;
180
181	0	if (st_index < 0)
182	0	return 0;
183
184	0	av_assert0(!data_arg->sampling);
185
186	0	if (av_strstart(line, "fmtp:", &p)) {
187	0	AVStream *stream = s->streams[st_index];
188	0	PayloadContext data0 = data_arg, data = &data0;
189	0	int ret = ff_parse_fmtp(s, stream, data, p, rfc4175_parse_fmtp);
190
191	0	if (!data->sampling \|\| !data->depth \|\| !data->width \|\| !data->height)
192	0	ret = AVERROR(EINVAL);
193
194	0	if (ret < 0)
195	0	goto fail;
196
197	0	ret = av_image_check_size(data->width, data->height, 0, s);
198	0	if (ret < 0)
199	0	goto fail;
200
201	0	stream->codecpar->width = data->width;
202	0	stream->codecpar->height = data->height;
203
204	0	ret = rfc4175_parse_format(stream, data);
205	0	av_freep(&data->sampling);
206	0	if (ret >= 0)
207	0	data_arg = data;
208	0	fail:
209	0	av_freep(&data->sampling);
210	0	return ret;
211	0	}
212
213	0	return 0;
214	0	}
215
216		static int rfc4175_finalize_packet(PayloadContext data, AVPacket pkt,
217		int stream_index)
218	0	{
219	0	int ret = AVERROR(EAGAIN);
220
221	0	pkt->stream_index = stream_index;
222	0	if (!data->interlaced \|\| data->field) {
223	0	ret = av_packet_from_data(pkt, data->frame, data->frame_size);
224	0	if (ret < 0) {
225	0	av_freep(&data->frame);
226	0	}
227	0	data->frame = NULL;
228	0	}
229
230	0	data->field = 0;
231
232	0	return ret;
233	0	}
234
235		static int rfc4175_handle_packet(AVFormatContext ctx, PayloadContext data,
236		AVStream st, AVPacket pkt, uint32_t *timestamp,
237		const uint8_t * buf, int len,
238		uint16_t seq, int flags)
239	0	{
240	0	int length, line, offset, cont, field;
241	0	const uint8_t headers, payload;
242	0	int payload_len;
243	0	int missed_last_packet = 0;
244
245	0	uint8_t *dest;
246
247	0	if (!buf) {
248	0	*timestamp = data->timestamp;
249	0	return rfc4175_finalize_packet(data, pkt, st->index);
250	0	}
251
252	0	headers = buf + 2; /* skip extended seqnum */
253	0	payload = buf + 2;
254	0	payload_len = len - 2;
255
256	0	if (*timestamp != data->timestamp) {
257	0	if (data->frame && (!data->interlaced \|\| data->field)) {
258		/*
259		* if we're here, it means that we missed the cue to return
260		* the previous AVPacket, that cue being the RTP_FLAG_MARKER
261		* in the last packet of either the previous frame (progressive)
262		* or the previous second field (interlace). Let's finalize the
263		* previous frame (or pair of fields) anyway by filling the AVPacket.
264		*/
265	0	av_log(ctx, AV_LOG_ERROR, "Missed previous RTP Marker\n");
266	0	missed_last_packet = rfc4175_finalize_packet(data, pkt, st->index) >= 0;
267	0	}
268
269	0	if (!data->frame)
270	0	data->frame = av_mallocz(data->frame_size + AV_INPUT_BUFFER_PADDING_SIZE);
271
272	0	if (missed_last_packet)
273	0	FFSWAP(uint32_t, data->timestamp, *timestamp);
274	0	else
275	0	data->timestamp = *timestamp;
276
277	0	if (!data->frame) {
278	0	av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");
279	0	return missed_last_packet ? 0 : AVERROR(ENOMEM);
280	0	}
281	0	}
282
283		/*
284		* looks for the 'Continuation bit' in scan lines' headers
285		* to find where data start
286		*/
287	0	do {
288	0	if (payload_len < 6)
289	0	goto invalid;
290
291	0	cont = payload[4] & 0x80;
292	0	payload += 6;
293	0	payload_len -= 6;
294	0	} while (cont);
295
296		/* and now iterate over every scan lines */
297	0	do {
298	0	int copy_offset;
299
300	0	if (payload_len < data->pgroup)
301	0	goto invalid;
302
303	0	length = (headers[0] << 8) \| headers[1];
304	0	field = (headers[2] & 0x80) >> 7;
305	0	line = ((headers[2] & 0x7f) << 8) \| headers[3];
306	0	offset = ((headers[4] & 0x7f) << 8) \| headers[5];
307	0	cont = headers[4] & 0x80;
308	0	headers += 6;
309	0	data->field = field;
310
311	0	if (!data->pgroup \|\| length % data->pgroup)
312	0	goto invalid;
313
314	0	if (length > payload_len)
315	0	length = payload_len;
316
317	0	if (data->interlaced)
318	0	line = 2 * line + field;
319
320	0	if (line >= data->height)
321	0	goto invalid;
322
323		/* prevent ill-formed packets to write after buffer's end */
324	0	copy_offset = (line * data->width + offset) * data->pgroup / data->xinc;
325	0	if (copy_offset + length > data->frame_size \|\| !data->frame)
326	0	goto invalid;
327
328	0	dest = data->frame + copy_offset;
329	0	memcpy(dest, payload, length);
330
331	0	payload += length;
332	0	payload_len -= length;
333	0	} while (cont);
334
335	0	if (missed_last_packet) {
336	0	return !!(flags & RTP_FLAG_MARKER);
337	0	} else if ((flags & RTP_FLAG_MARKER)) {
338	0	return rfc4175_finalize_packet(data, pkt, st->index);
339	0	}
340
341	0	return AVERROR(EAGAIN);
342
343	0	invalid:
344	0	return missed_last_packet ? 0 : AVERROR_INVALIDDATA;
345	0	}
346
347		static void rfc4175_close_context(PayloadContext *data)
348	0	{
349	0	av_freep(&data->frame);
350	0	}
351
352		const RTPDynamicProtocolHandler ff_rfc4175_rtp_handler = {
353		.enc_name = "raw",
354		.codec_type = AVMEDIA_TYPE_VIDEO,
355		.codec_id = AV_CODEC_ID_NONE,
356		.priv_data_size = sizeof(PayloadContext),
357		.parse_sdp_a_line = rfc4175_parse_sdp_line,
358		.parse_packet = rfc4175_handle_packet,
359		.close = rfc4175_close_context,
360		};