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rtpdec_vp8: Make the depacketizer implement the latest spec draft

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Not all details are implemented, but it's enough for proper
playback as long as there is no packet loss.

Tested to work with the packetizer in gstreamer (which although
uses a different codec name, to clarify that it is still a spec
draft).

Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Martin Storsjö 2012-10-08 22:25:55 +03:00
parent 27a310e381
commit 66d652cbf3
1 changed files with 63 additions and 52 deletions
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115
libavformat/rtpdec_vp8.c
View File

@ -1,6 +1,7 @@
/*
* RTP VP8 Depacketizer
* Copyright (c) 2010 Josh Allmann
* Copyright (c) 2012 Martin Storsjo
*
* This file is part of Libav.
*
@ -23,7 +24,7 @@
* @file
* @brief RTP support for the VP8 payload
* @author Josh Allmann <joshua.allmann@gmail.com>
* @see http://www.webmproject.org/code/specs/rtp/
* @see http://tools.ietf.org/html/draft-ietf-payload-vp8-05
*/
#include "libavcodec/bytestream.h"
@ -33,14 +34,12 @@
struct PayloadContext {
AVIOContext *data;
uint32_t timestamp;
int is_keyframe;
};
static void prepare_packet(AVPacket *pkt, PayloadContext *vp8, int stream)
{
av_init_packet(pkt);
pkt->stream_index = stream;
pkt->flags = vp8->is_keyframe ? AV_PKT_FLAG_KEY : 0;
pkt->size = avio_close_dyn_buf(vp8->data, &pkt->data);
pkt->destruct = av_destruct_packet;
vp8->data = NULL;
@ -54,70 +53,84 @@ static int vp8_handle_packet(AVFormatContext *ctx,
const uint8_t *buf,
int len, int flags)
{
int start_packet, end_packet, has_au, ret = AVERROR(EAGAIN);
int start_partition, end_packet;
int extended_bits, non_ref, part_id;
int pictureid_present = 0, tl0picidx_present = 0, tid_present = 0,
keyidx_present = 0;
int pictureid = -1, keyidx = -1;
if (!buf) {
// only called when vp8_handle_packet returns 1
if (!vp8->data) {
av_log(ctx, AV_LOG_ERROR, "Invalid VP8 data passed\n");
return AVERROR_INVALIDDATA;
}
prepare_packet(pkt, vp8, st->index);
*timestamp = vp8->timestamp;
return 0;
}
if (len < 1)
return AVERROR_INVALIDDATA;
start_packet = *buf & 1;
end_packet = flags & RTP_FLAG_MARKER;
has_au = *buf & 2;
extended_bits = buf[0] & 0x80;
non_ref = buf[0] & 0x20;
start_partition = buf[0] & 0x10;
part_id = buf[0] & 0x0f;
end_packet = flags & RTP_FLAG_MARKER;
buf++;
len--;
if (extended_bits) {
if (len < 1)
return AVERROR_INVALIDDATA;
pictureid_present = buf[0] & 0x80;
tl0picidx_present = buf[0] & 0x40;
tid_present = buf[0] & 0x20;
keyidx_present = buf[0] & 0x10;
buf++;
len--;
}
if (pictureid_present) {
if (len < 1)
return AVERROR_INVALIDDATA;
if (buf[0] & 0x80) {
if (len < 2)
return AVERROR_INVALIDDATA;
pictureid = AV_RB16(buf) & 0x7fff;
buf += 2;
len -= 2;
} else {
pictureid = buf[0] & 0x7f;
buf++;
len--;
}
}
if (tl0picidx_present) {
// Ignoring temporal level zero index
buf++;
len--;
}
if (tid_present || keyidx_present) {
// Ignoring temporal layer index and layer sync bit
if (len < 1)
return AVERROR_INVALIDDATA;
if (keyidx_present)
keyidx = buf[0] & 0x1f;
buf++;
len--;
}
if (len < 1)
return AVERROR_INVALIDDATA;
if (start_packet) {
if (start_partition && part_id == 0) {
int res;
uint32_t ts = *timestamp;
if (vp8->data) {
// missing end marker; return old frame anyway. untested
prepare_packet(pkt, vp8, st->index);
*timestamp = vp8->timestamp; // reset timestamp from old frame
// if current frame fits into one rtp packet, need to hold
// that for the next av_get_packet call
ret = end_packet ? 1 : 0;
uint8_t *tmp;
avio_close_dyn_buf(vp8->data, &tmp);
av_free(tmp);
vp8->data = NULL;
}
if ((res = avio_open_dyn_buf(&vp8->data)) < 0)
return res;
vp8->is_keyframe = *buf & 1;
vp8->timestamp = ts;
vp8->timestamp = *timestamp;
}
if (!vp8->data || vp8->timestamp != *timestamp && ret == AVERROR(EAGAIN)) {
if (!vp8->data || vp8->timestamp != *timestamp) {
av_log(ctx, AV_LOG_WARNING,
"Received no start marker; dropping frame\n");
return AVERROR(EAGAIN);
}
// cycle through VP8AU headers if needed
// not tested with actual VP8AUs
while (len) {
int au_len = len;
if (has_au && len > 2) {
au_len = AV_RB16(buf);
buf += 2;
len -= 2;
if (buf + au_len > buf + len) {
av_log(ctx, AV_LOG_ERROR, "Invalid VP8AU length\n");
return AVERROR_INVALIDDATA;
}
}
avio_write(vp8->data, buf, au_len);
buf += au_len;
len -= au_len;
}
if (ret != AVERROR(EAGAIN)) // did we miss a end marker?
return ret;
avio_write(vp8->data, buf, len);
if (end_packet) {
prepare_packet(pkt, vp8, st->index);
@ -129,8 +142,6 @@ static int vp8_handle_packet(AVFormatContext *ctx,
static PayloadContext *vp8_new_context(void)
{
av_log(NULL, AV_LOG_ERROR, "RTP VP8 payload implementation is incompatible "
"with the latest spec drafts.\n");
return av_mallocz(sizeof(PayloadContext));
}