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ffmpeg/libavformat/rtpdec_vp9.c

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/*
* RTP parser for VP9 payload format (draft version 0) - experimental
* Copyright (c) 2015 Thomas Volkert <thomas@homer-conferencing.com>
*
* 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
*
*/
#include "libavcodec/bytestream.h"
#include "rtpdec_formats.h"
#define RTP_VP9_DESC_REQUIRED_SIZE 1
struct PayloadContext {
AVIOContext *buf;
uint32_t timestamp;
};
static void vp9_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 int vp9_init(AVFormatContext *ctx, int st_index,
PayloadContext *data)
{
av_dlog(ctx, "vp9_init() for stream %d\n", st_index);
av_log(ctx, AV_LOG_WARNING,
"RTP/VP9 support is still experimental\n");
if (st_index < 0)
return 0;
ctx->streams[st_index]->need_parsing = AVSTREAM_PARSE_FULL;
return 0;
}
static int vp9_handle_packet(AVFormatContext *ctx, PayloadContext *rtp_vp9_ctx,
AVStream *st, AVPacket *pkt, uint32_t *timestamp,
const uint8_t *buf, int len, uint16_t seq,
int flags)
{
int has_pic_id, has_layer_idc, has_ref_idc, has_ss_data, has_su_data;
av_unused int pic_id = 0, non_key_frame = 0;
av_unused int layer_temporal = -1, layer_spatial = -1, layer_quality = -1;
int ref_fields = 0, has_ref_field_ext_pic_id = 0;
int first_fragment, last_fragment;
int res = 0;
/* drop data of previous packets in case of non-continuous (lossy) packet stream */
if (rtp_vp9_ctx->buf && rtp_vp9_ctx->timestamp != *timestamp) {
vp9_free_dyn_buffer(&rtp_vp9_ctx->buf);
}
/* sanity check for size of input packet: 1 byte payload at least */
if (len < RTP_VP9_DESC_REQUIRED_SIZE + 1) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet, got %d bytes\n", len);
return AVERROR_INVALIDDATA;
}
/*
decode the required VP9 payload descriptor according to section 4.2 of the spec.:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|I|L|F|B|E|V|U|-| (REQUIRED)
+-+-+-+-+-+-+-+-+
I: PictureID present
L: Layer indices present
F: Reference indices present
B: Start of VP9 frame
E: End of picture
V: Scalability Structure (SS) present
U: Scalability Structure Update (SU) present
*/
has_pic_id = buf[0] & 0x80;
has_layer_idc = buf[0] & 0x40;
has_ref_idc = buf[0] & 0x20;
first_fragment = buf[0] & 0x10;
last_fragment = buf[0] & 0x08;
has_ss_data = buf[0] & 0x04;
has_su_data = buf[0] & 0x02;
/* sanity check for markers: B should always be equal to the RTP M marker */
if (last_fragment >> 2 != flags & RTP_FLAG_MARKER) {
av_log(ctx, AV_LOG_ERROR, "Invalid combination of B and M marker\n");
return AVERROR_INVALIDDATA;
}
/* pass the extensions field */
buf += RTP_VP9_DESC_REQUIRED_SIZE;
len -= RTP_VP9_DESC_REQUIRED_SIZE;
/*
decode the 1-byte/2-byte picture ID:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
I: |M|PICTURE ID | (RECOMMENDED)
+-+-+-+-+-+-+-+-+
M: | EXTENDED PID | (RECOMMENDED)
+-+-+-+-+-+-+-+-+
M: The most significant bit of the first octet is an extension flag.
PictureID: 8 or 16 bits including the M bit.
*/
if (has_pic_id) {
if (len < 1) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
return AVERROR_INVALIDDATA;
}
/* check for 1-byte or 2-byte picture index */
if (buf[0] & 0x80) {
if (len < 2) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
return AVERROR_INVALIDDATA;
}
pic_id = AV_RB16(buf) & 0x7fff;
buf += 2;
len -= 2;
} else {
pic_id = buf[0] & 0x7f;
buf++;
len--;
}
}
/*
decode layer indices
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
L: | T | S | Q | R | (CONDITIONALLY RECOMMENDED)
+-+-+-+-+-+-+-+-+
T, S and Q are 2-bit indices for temporal, spatial, and quality layers.
If "F" is set in the initial octet, R is 2 bits representing the number
of reference fields this frame refers to.
*/
if (has_layer_idc) {
if (len < 1) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet");
return AVERROR_INVALIDDATA;
}
layer_temporal = buf[0] & 0xC0;
layer_spatial = buf[0] & 0x30;
layer_quality = buf[0] & 0x0C;
if (has_ref_idc) {
ref_fields = buf[0] & 0x03;
if (ref_fields)
non_key_frame = 1;
}
buf++;
len--;
}
/*
decode the reference fields
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ -\
F: | PID |X| RS| RQ| (OPTIONAL) .
+-+-+-+-+-+-+-+-+ . - R times
X: | EXTENDED PID | (OPTIONAL) .
+-+-+-+-+-+-+-+-+ -/
PID: The relative Picture ID referred to by this frame.
RS and RQ: The spatial and quality layer IDs.
X: 1 if this layer index has an extended relative Picture ID.
*/
if (has_ref_idc) {
while (ref_fields) {
if (len < 1) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
return AVERROR_INVALIDDATA;
}
has_ref_field_ext_pic_id = buf[0] & 0x10;
/* pass ref. field */
if (has_ref_field_ext_pic_id) {
if (len < 2) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
return AVERROR_INVALIDDATA;
}
/* ignore ref. data */
buf += 2;
len -= 2;
} else {
/* ignore ref. data */
buf++;
len--;
}
ref_fields--;
}
}
/*
decode the scalability structure (SS)
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
V: | PATTERN LENGTH|
+-+-+-+-+-+-+-+-+ -\
| T | S | Q | R | (OPTIONAL) .
+-+-+-+-+-+-+-+-+ -\ .
| PID |X| RS| RQ| (OPTIONAL) . . - PAT. LEN. times
+-+-+-+-+-+-+-+-+ . - R times .
X: | EXTENDED PID | (OPTIONAL) . .
+-+-+-+-+-+-+-+-+ -/ -/
PID: The relative Picture ID referred to by this frame.
RS and RQ: The spatial and quality layer IDs.
X: 1 if this layer index has an extended relative Picture ID.
*/
if (has_ss_data) {
avpriv_report_missing_feature(ctx, "VP9 scalability structure data\n");
return AVERROR_PATCHWELCOME;
}
/*
decode the scalability update structure (SU)
spec. is tbd
*/
if (has_su_data) {
avpriv_report_missing_feature(ctx, "VP9 scalability update structure data\n");
return AVERROR_PATCHWELCOME;
}
/*
decode the VP9 payload header
spec. is tbd
*/
//XXX: implement when specified
/* sanity check: 1 byte payload as minimum */
if (len < 1) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
return AVERROR_INVALIDDATA;
}
/* start frame buffering with new dynamic buffer */
if (!rtp_vp9_ctx->buf) {
/* sanity check: a new frame should have started */
if (first_fragment) {
res = avio_open_dyn_buf(&rtp_vp9_ctx->buf);
if (res < 0)
return res;
/* update the timestamp in the frame packet with the one from the RTP packet */
rtp_vp9_ctx->timestamp = *timestamp;
} else {
/* frame not started yet, need more packets */
return AVERROR(EAGAIN);
}
}
/* write the fragment to the dyn. buffer */
avio_write(rtp_vp9_ctx->buf, buf, len);
/* do we need more fragments? */
if (!last_fragment)
return AVERROR(EAGAIN);
/* close frame buffering and create resulting A/V packet */
res = ff_rtp_finalize_packet(pkt, &rtp_vp9_ctx->buf, st->index);
if (res < 0)
return res;
return 0;
}
RTPDynamicProtocolHandler ff_vp9_dynamic_handler = {
.enc_name = "VP9",
.codec_type = AVMEDIA_TYPE_VIDEO,
.codec_id = AV_CODEC_ID_VP9,
.init = vp9_init,
.priv_data_size = sizeof(PayloadContext),
.parse_packet = vp9_handle_packet
};
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