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rtp: Initial H.261 support

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The packetizer only supports splitting at GOB headers - if
such aren't available frequently enough, it splits at any
random byte offset (not at a macroblock boundary either, which
would be allowed by the spec) and sends a payload header pretend
that it starts with a GOB header.

As long as a receiver doesn't try to handle such cases cleverly
but just drops broken frames, this shouldn't matter too much
in practice.

Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Thomas Volkert 2014-12-06 19:54:07 +01:00 committed by Martin Storsjö
parent adc214e679
commit a505c0d737
10 changed files with 343 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
Changelog
View File

@ -7,6 +7,7 @@ version <next>:
- avplay now exits by default at the end of playback
- XCB-based screen-grabber
- creating DASH compatible fragmented MP4, MPEG-DASH segmenting muxer
- H.261 RTP payload format (RFC 4587) depacketizer and experimental packetizer
version 11:

2
libavformat/Makefile
View File

@ -32,6 +32,7 @@ OBJS-$(CONFIG_RTPDEC) += rdt.o \
rtpdec_amr.o \
rtpdec_asf.o \
rtpdec_g726.o \
rtpdec_h261.o \
rtpdec_h263.o \
rtpdec_h263_rfc2190.o \
rtpdec_h264.o \
@ -290,6 +291,7 @@ OBJS-$(CONFIG_RTP_MUXER) += rtp.o \
rtpenc_aac.o \
rtpenc_latm.o \
rtpenc_amr.o \
rtpenc_h261.o \
rtpenc_h263.o \
rtpenc_h263_rfc2190.o \
rtpenc_hevc.o \

1
libavformat/rtpdec.c
View File

@ -66,6 +66,7 @@ void ff_register_rtp_dynamic_payload_handlers(void)
ff_register_dynamic_payload_handler(&ff_g726_24_dynamic_handler);
ff_register_dynamic_payload_handler(&ff_g726_32_dynamic_handler);
ff_register_dynamic_payload_handler(&ff_g726_40_dynamic_handler);
ff_register_dynamic_payload_handler(&ff_h261_dynamic_handler);
ff_register_dynamic_payload_handler(&ff_h263_1998_dynamic_handler);
ff_register_dynamic_payload_handler(&ff_h263_2000_dynamic_handler);
ff_register_dynamic_payload_handler(&ff_h263_rfc2190_dynamic_handler);

1
libavformat/rtpdec_formats.h
View File

@ -41,6 +41,7 @@ extern RTPDynamicProtocolHandler ff_g726_16_dynamic_handler;
extern RTPDynamicProtocolHandler ff_g726_24_dynamic_handler;
extern RTPDynamicProtocolHandler ff_g726_32_dynamic_handler;
extern RTPDynamicProtocolHandler ff_g726_40_dynamic_handler;
extern RTPDynamicProtocolHandler ff_h261_dynamic_handler;
extern RTPDynamicProtocolHandler ff_h263_1998_dynamic_handler;
extern RTPDynamicProtocolHandler ff_h263_2000_dynamic_handler;
extern RTPDynamicProtocolHandler ff_h263_rfc2190_dynamic_handler;

202
libavformat/rtpdec_h261.c Normal file
View File

@ -0,0 +1,202 @@
/*
* RTP parser for H.261 payload format (RFC 4587)
* Copyright (c) 2014 Thomas Volkert <thomas@homer-conferencing.com>
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavcodec/get_bits.h"
#include "avformat.h"
#include "rtpdec_formats.h"
#define RTP_H261_PAYLOAD_HEADER_SIZE 4
struct PayloadContext {
AVIOContext *buf;
uint8_t endbyte;
int endbyte_bits;
uint32_t timestamp;
};
static av_cold PayloadContext *h261_new_context(void)
{
return av_mallocz(sizeof(PayloadContext));
}
static void h261_free_dyn_buffer(AVIOContext **dyn_buf)
{
uint8_t *ptr_dyn_buffer;
avio_close_dyn_buf(*dyn_buf, &ptr_dyn_buffer);
av_free(ptr_dyn_buffer);
*dyn_buf = NULL;
}
static av_cold void h261_free_context(PayloadContext *pl_ctx)
{
/* return if context is invalid */
if (!pl_ctx)
return;
/* free buffer if it is valid */
if (pl_ctx->buf) {
h261_free_dyn_buffer(&pl_ctx->buf);
}
/* free context */
av_free(pl_ctx);
}
static av_cold int h261_init(AVFormatContext *ctx, int st_index,
PayloadContext *data)
{
if (st_index < 0)
return 0;
ctx->streams[st_index]->need_parsing = AVSTREAM_PARSE_FULL;
return 0;
}
static int h261_handle_packet(AVFormatContext *ctx, PayloadContext *rtp_h261_ctx,
AVStream *st, AVPacket *pkt, uint32_t *timestamp,
const uint8_t *buf, int len, uint16_t seq,
int flags)
{
int sbit, ebit, gobn, mbap, quant;
int res;
/* drop data of previous packets in case of non-continuous (lossy) packet stream */
if (rtp_h261_ctx->buf && rtp_h261_ctx->timestamp != *timestamp) {
h261_free_dyn_buffer(&rtp_h261_ctx->buf);
rtp_h261_ctx->endbyte_bits = 0;
}
/* sanity check for size of input packet: 1 byte payload at least */
if (len < RTP_H261_PAYLOAD_HEADER_SIZE + 1) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/H.261 packet, got %d bytes\n", len);
return AVERROR_INVALIDDATA;
}
/*
* decode the H.261 payload header according to section 4.1 of RFC 4587:
* (uses 4 bytes between RTP header and H.261 stream per packet)
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |SBIT |EBIT |I|V| GOBN | MBAP | QUANT | HMVD | VMVD |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* Start bit position (SBIT): 3 bits
* End bit position (EBIT): 3 bits
* INTRA-frame encoded data (I): 1 bit
* Motion Vector flag (V): 1 bit
* GOB number (GOBN): 4 bits
* Macroblock address predictor (MBAP): 5 bits
* Quantizer (QUANT): 5 bits
* Horizontal motion vector data (HMVD): 5 bits
* Vertical motion vector data (VMVD): 5 bits
*/
sbit = (buf[0] >> 5) & 0x07;
ebit = (buf[0] >> 2) & 0x07;
gobn = (buf[1] >> 4) & 0x0f;
mbap = ((buf[1] << 1) & 0x1e) | ((buf[2] >> 7) & 0x01);
quant = (buf[2] >> 2) & 0x1f;
/* pass the H.261 payload header and continue with the actual payload */
buf += RTP_H261_PAYLOAD_HEADER_SIZE;
len -= RTP_H261_PAYLOAD_HEADER_SIZE;
/* start frame buffering with new dynamic buffer */
if (!rtp_h261_ctx->buf) {
/* sanity check: a new frame starts with gobn=0, sbit=0, mbap=0, quant=0 */
if (!gobn && !sbit && !mbap && !quant) {
res = avio_open_dyn_buf(&rtp_h261_ctx->buf);
if (res < 0)
return res;
/* update the timestamp in the frame packet with the one from the RTP packet */
rtp_h261_ctx->timestamp = *timestamp;
} else {
/* frame not started yet, need more packets */
return AVERROR(EAGAIN);
}
}
/* do the "byte merging" at the boundaries of two consecutive frame fragments */
if (rtp_h261_ctx->endbyte_bits || sbit) {
if (rtp_h261_ctx->endbyte_bits == sbit) {
rtp_h261_ctx->endbyte |= buf[0] & (0xff >> sbit);
rtp_h261_ctx->endbyte_bits = 0;
buf++;
len--;
avio_w8(rtp_h261_ctx->buf, rtp_h261_ctx->endbyte);
} else {
/* ebit/sbit values inconsistent, assuming packet loss */
GetBitContext gb;
init_get_bits(&gb, buf, len*8 - ebit);
skip_bits(&gb, sbit);
if (rtp_h261_ctx->endbyte_bits) {
rtp_h261_ctx->endbyte |= get_bits(&gb, 8 - rtp_h261_ctx->endbyte_bits);
avio_w8(rtp_h261_ctx->buf, rtp_h261_ctx->endbyte);
}
while (get_bits_left(&gb) >= 8)
avio_w8(rtp_h261_ctx->buf, get_bits(&gb, 8));
rtp_h261_ctx->endbyte_bits = get_bits_left(&gb);
if (rtp_h261_ctx->endbyte_bits)
rtp_h261_ctx->endbyte = get_bits(&gb, rtp_h261_ctx->endbyte_bits) <<
(8 - rtp_h261_ctx->endbyte_bits);
ebit = 0;
len = 0;
}
}
if (ebit) {
if (len > 0)
avio_write(rtp_h261_ctx->buf, buf, len - 1);
rtp_h261_ctx->endbyte_bits = 8 - ebit;
rtp_h261_ctx->endbyte = buf[len - 1] & (0xff << ebit);
} else {
avio_write(rtp_h261_ctx->buf, buf, len);
}
/* RTP marker bit means: last fragment of current frame was received;
otherwise, an additional fragment is needed for the current frame */
if (!(flags & RTP_FLAG_MARKER))
return AVERROR(EAGAIN);
/* write the completed last byte from the "byte merging" */
if (rtp_h261_ctx->endbyte_bits)
avio_w8(rtp_h261_ctx->buf, rtp_h261_ctx->endbyte);
rtp_h261_ctx->endbyte_bits = 0;
/* close frame buffering and create resulting A/V packet */
res = ff_rtp_finalize_packet(pkt, &rtp_h261_ctx->buf, st->index);
if (res < 0)
return res;
return 0;
}
RTPDynamicProtocolHandler ff_h261_dynamic_handler = {
.enc_name = "H261",
.codec_type = AVMEDIA_TYPE_VIDEO,
.codec_id = AV_CODEC_ID_H261,
.init = h261_init,
.alloc = h261_new_context,
.free = h261_free_context,
.parse_packet = h261_handle_packet,
.static_payload_id = 31,
};

19
libavformat/rtpenc.c
View File

@ -49,6 +49,7 @@ static const AVClass rtp_muxer_class = {
static int is_supported(enum AVCodecID id)
{
switch(id) {
case AV_CODEC_ID_H261:
case AV_CODEC_ID_H263:
case AV_CODEC_ID_H263P:
case AV_CODEC_ID_H264:
@ -88,7 +89,7 @@ static int is_supported(enum AVCodecID id)
static int rtp_write_header(AVFormatContext *s1)
{
RTPMuxContext *s = s1->priv_data;
int n;
int n, ret = AVERROR(EINVAL);
AVStream *st;
if (s1->nb_streams != 1) {
@ -191,6 +192,17 @@ static int rtp_write_header(AVFormatContext *s1)
s->max_payload_size = n * TS_PACKET_SIZE;
s->buf_ptr = s->buf;
break;
case AV_CODEC_ID_H261:
if (s1->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL) {
av_log(s, AV_LOG_ERROR,
"Packetizing H261 is experimental and produces incorrect "
"packetization for cases where GOBs don't fit into packets "
"(even though most receivers may handle it just fine). "
"Please set -f_strict experimental in order to enable it.\n");
ret = AVERROR_EXPERIMENTAL;
goto fail;
}
break;
case AV_CODEC_ID_H264:
/* check for H.264 MP4 syntax */
if (st->codec->extradata_size > 4 && st->codec->extradata[0] == 1) {
@ -273,7 +285,7 @@ defaultcase:
fail:
av_freep(&s->buf);
return AVERROR(EINVAL);
return ret;
}
/* send an rtcp sender report packet */
@ -567,6 +579,9 @@ static int rtp_write_packet(AVFormatContext *s1, AVPacket *pkt)
case AV_CODEC_ID_H264:
ff_rtp_send_h264(s1, pkt->data, size);
break;
case AV_CODEC_ID_H261:
ff_rtp_send_h261(s1, pkt->data, size);
break;
case AV_CODEC_ID_H263:
if (s->flags & FF_RTP_FLAG_RFC2190) {
int mb_info_size = 0;

1
libavformat/rtpenc.h
View File

@ -81,6 +81,7 @@ typedef struct RTPMuxContext RTPMuxContext;
void ff_rtp_send_data(AVFormatContext *s1, const uint8_t *buf1, int len, int m);
void ff_rtp_send_h264(AVFormatContext *s1, const uint8_t *buf1, int size);
void ff_rtp_send_h261(AVFormatContext *s1, const uint8_t *buf1, int size);
void ff_rtp_send_h263(AVFormatContext *s1, const uint8_t *buf1, int size);
void ff_rtp_send_h263_rfc2190(AVFormatContext *s1, const uint8_t *buf1, int size,
const uint8_t *mb_info, int mb_info_size);

102
libavformat/rtpenc_h261.c Normal file
View File

@ -0,0 +1,102 @@
/*
* RTP packetization for H.261 video (RFC 4587)
* Copyright (c) 2014 Thomas Volkert <thomas@homer-conferencing.com>
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avformat.h"
#include "rtpenc.h"
#define RTP_H261_HEADER_SIZE 4
static const uint8_t *find_resync_marker_reverse(const uint8_t *restrict start,
const uint8_t *restrict end)
{
const uint8_t *p = end - 1;
start += 1; /* Make sure we never return the original start. */
for (; p > start; p--) {
if (p[0] == 0 && p[1] == 1)
return p;
}
return end;
}
void ff_rtp_send_h261(AVFormatContext *ctx, const uint8_t *frame_buf, int frame_size)
{
int cur_frame_size;
int last_packet_of_frame;
RTPMuxContext *rtp_ctx = ctx->priv_data;
/* use the default 90 KHz time stamp */
rtp_ctx->timestamp = rtp_ctx->cur_timestamp;
/* continue as long as not all frame data is processed */
while (frame_size > 0) {
/*
* encode the H.261 payload header according to section 4.1 of RFC 4587:
* (uses 4 bytes between RTP header and H.261 stream per packet)
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |SBIT |EBIT |I|V| GOBN | MBAP | QUANT | HMVD | VMVD |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* Start bit position (SBIT): 3 bits
* End bit position (EBIT): 3 bits
* INTRA-frame encoded data (I): 1 bit
* Motion Vector flag (V): 1 bit
* GOB number (GOBN): 4 bits
* Macroblock address predictor (MBAP): 5 bits
* Quantizer (QUANT): 5 bits
* Horizontal motion vector data (HMVD): 5 bits
* Vertical motion vector data (VMVD): 5 bits
*/
rtp_ctx->buf[0] = 1; /* sbit=0, ebit=0, i=0, v=1 */
rtp_ctx->buf[1] = 0; /* gobn=0, mbap=0 */
rtp_ctx->buf[2] = 0; /* quant=0, hmvd=5 */
rtp_ctx->buf[3] = 0; /* vmvd=0 */
if (frame_size < 2 || frame_buf[0] != 0 || frame_buf[1] != 1) {
/* A full, correct fix for this would be to make the H261 encoder
* support inserting extra GOB headers (triggered by setting e.g.
* "-ps 1"), and including information about macroblock boundaries
* (such as for h263_rfc2190). */
av_log(ctx, AV_LOG_WARNING,
"RTP/H261 packet not cut at a GOB boundary, not signaled correctly\n");
}
cur_frame_size = FFMIN(rtp_ctx->max_payload_size - RTP_H261_HEADER_SIZE, frame_size);
/* look for a better place to split the frame into packets */
if (cur_frame_size < frame_size) {
const uint8_t *packet_end = find_resync_marker_reverse(frame_buf,
frame_buf + cur_frame_size);
cur_frame_size = packet_end - frame_buf;
}
/* calculate the "marker" bit for the RTP header */
last_packet_of_frame = cur_frame_size == frame_size;
/* complete and send RTP packet */
memcpy(&rtp_ctx->buf[RTP_H261_HEADER_SIZE], frame_buf, cur_frame_size);
ff_rtp_send_data(ctx, rtp_ctx->buf, RTP_H261_HEADER_SIZE + cur_frame_size, last_packet_of_frame);
frame_buf += cur_frame_size;
frame_size -= cur_frame_size;
}
}

14
libavformat/sdp.c
View File

@ -498,6 +498,20 @@ static char *sdp_write_media_attributes(char *buff, int size, AVCodecContext *c,
payload_type, mode, config ? config : "");
break;
}
case AV_CODEC_ID_H261:
{
const char *pic_fmt = NULL;
/* only QCIF and CIF are specified as supported in RFC 4587 */
if (c->width == 176 && c->height == 144)
pic_fmt = "QCIF=1";
else if (c->width == 352 && c->height == 288)
pic_fmt = "CIF=1";
if (payload_type >= RTP_PT_PRIVATE)
av_strlcatf(buff, size, "a=rtpmap:%d H261/90000\r\n", payload_type);
if (pic_fmt)
av_strlcatf(buff, size, "a=fmtp:%d %s\r\n", payload_type, pic_fmt);
break;
}
case AV_CODEC_ID_H263:
case AV_CODEC_ID_H263P:
/* a=framesize is required by 3GPP TS 26.234 (PSS). It

4
libavformat/version.h
View File

@ -30,8 +30,8 @@
#include "libavutil/version.h"
#define LIBAVFORMAT_VERSION_MAJOR 56
#define LIBAVFORMAT_VERSION_MINOR 7
#define LIBAVFORMAT_VERSION_MICRO 2
#define LIBAVFORMAT_VERSION_MINOR 8
#define LIBAVFORMAT_VERSION_MICRO 0
#define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
LIBAVFORMAT_VERSION_MINOR, \