289 lines
9.8 KiB
C
289 lines
9.8 KiB
C
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/*
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* RTP VP8 Depacketizer
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* Copyright (c) 2010 Josh Allmann
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* Copyright (c) 2012 Martin Storsjo
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* @brief RTP support for the VP8 payload
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* @author Josh Allmann <joshua.allmann@gmail.com>
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* @see http://tools.ietf.org/html/draft-ietf-payload-vp8-05
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*/
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#include "libavcodec/bytestream.h"
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#include "avio_internal.h"
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#include "rtpdec_formats.h"
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struct PayloadContext {
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AVIOContext *data;
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uint32_t timestamp;
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int is_keyframe;
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/* If sequence_ok is set, we keep returning data (even if we might have
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* lost some data, but we haven't lost any too critical data that would
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* cause the decoder to desynchronize and output random garbage).
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*/
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int sequence_ok;
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int first_part_size;
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uint16_t prev_seq;
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int prev_pictureid;
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int broken_frame;
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/* If sequence_dirty is set, we have lost some data (critical or
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* non-critical) and decoding will have some sort of artifacts, and
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* we thus should request a new keyframe.
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*/
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int sequence_dirty;
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int got_keyframe;
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};
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static int vp8_broken_sequence(AVFormatContext *ctx, PayloadContext *vp8,
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const char *msg)
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{
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vp8->sequence_ok = 0;
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av_log(ctx, AV_LOG_WARNING, "%s", msg);
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ffio_free_dyn_buf(&vp8->data);
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return AVERROR(EAGAIN);
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}
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static int vp8_handle_packet(AVFormatContext *ctx, PayloadContext *vp8,
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AVStream *st, AVPacket *pkt, uint32_t *timestamp,
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const uint8_t *buf, int len, uint16_t seq,
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int flags)
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{
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int start_partition, end_packet;
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int extended_bits, part_id;
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int pictureid_present = 0, tl0picidx_present = 0, tid_present = 0,
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keyidx_present = 0;
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int pictureid = -1, pictureid_mask = 0;
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int returned_old_frame = 0;
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uint32_t old_timestamp = 0;
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if (!buf) {
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if (vp8->data) {
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int ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
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if (ret < 0)
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return ret;
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*timestamp = vp8->timestamp;
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if (vp8->sequence_dirty)
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pkt->flags |= AV_PKT_FLAG_CORRUPT;
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return 0;
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}
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return AVERROR(EAGAIN);
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}
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if (len < 1)
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return AVERROR_INVALIDDATA;
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extended_bits = buf[0] & 0x80;
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start_partition = buf[0] & 0x10;
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part_id = buf[0] & 0x0f;
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end_packet = flags & RTP_FLAG_MARKER;
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buf++;
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len--;
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if (extended_bits) {
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if (len < 1)
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return AVERROR_INVALIDDATA;
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pictureid_present = buf[0] & 0x80;
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tl0picidx_present = buf[0] & 0x40;
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tid_present = buf[0] & 0x20;
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keyidx_present = buf[0] & 0x10;
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buf++;
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len--;
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}
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if (pictureid_present) {
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if (len < 1)
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return AVERROR_INVALIDDATA;
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if (buf[0] & 0x80) {
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if (len < 2)
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return AVERROR_INVALIDDATA;
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pictureid = AV_RB16(buf) & 0x7fff;
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pictureid_mask = 0x7fff;
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buf += 2;
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len -= 2;
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} else {
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pictureid = buf[0] & 0x7f;
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pictureid_mask = 0x7f;
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buf++;
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len--;
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}
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}
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if (tl0picidx_present) {
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// Ignoring temporal level zero index
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buf++;
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len--;
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}
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if (tid_present || keyidx_present) {
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// Ignoring temporal layer index, layer sync bit and keyframe index
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buf++;
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len--;
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}
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if (len < 1)
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return AVERROR_INVALIDDATA;
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if (start_partition && part_id == 0 && len >= 3) {
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int res;
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int non_key = buf[0] & 0x01;
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if (!non_key) {
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ffio_free_dyn_buf(&vp8->data);
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// Keyframe, decoding ok again
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vp8->sequence_ok = 1;
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vp8->sequence_dirty = 0;
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vp8->got_keyframe = 1;
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} else {
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int can_continue = vp8->data && !vp8->is_keyframe &&
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avio_tell(vp8->data) >= vp8->first_part_size;
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if (!vp8->sequence_ok)
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return AVERROR(EAGAIN);
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if (!vp8->got_keyframe)
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return vp8_broken_sequence(ctx, vp8, "Keyframe missing\n");
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if (pictureid >= 0) {
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if (pictureid != ((vp8->prev_pictureid + 1) & pictureid_mask)) {
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return vp8_broken_sequence(ctx, vp8,
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"Missed a picture, sequence broken\n");
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} else {
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if (vp8->data && !can_continue)
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return vp8_broken_sequence(ctx, vp8,
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"Missed a picture, sequence broken\n");
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}
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} else {
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uint16_t expected_seq = vp8->prev_seq + 1;
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int16_t diff = seq - expected_seq;
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if (vp8->data) {
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// No picture id, so we can't know if missed packets
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// contained any new frames. If diff == 0, we did get
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// later packets from the same frame (matching timestamp),
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// so we know we didn't miss any frame. If diff == 1 and
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// we still have data (not flushed by the end of frame
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// marker), the single missed packet must have been part
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// of the same frame.
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if ((diff == 0 || diff == 1) && can_continue) {
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// Proceed with what we have
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} else {
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return vp8_broken_sequence(ctx, vp8,
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"Missed too much, sequence broken\n");
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}
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} else {
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if (diff != 0)
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return vp8_broken_sequence(ctx, vp8,
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"Missed unknown data, sequence broken\n");
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}
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}
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if (vp8->data) {
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vp8->sequence_dirty = 1;
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if (avio_tell(vp8->data) >= vp8->first_part_size) {
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int ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
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if (ret < 0)
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return ret;
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pkt->flags |= AV_PKT_FLAG_CORRUPT;
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returned_old_frame = 1;
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old_timestamp = vp8->timestamp;
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} else {
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// Shouldn't happen
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ffio_free_dyn_buf(&vp8->data);
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}
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}
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}
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vp8->first_part_size = (AV_RL16(&buf[1]) << 3 | buf[0] >> 5) + 3;
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if ((res = avio_open_dyn_buf(&vp8->data)) < 0)
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return res;
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vp8->timestamp = *timestamp;
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vp8->broken_frame = 0;
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vp8->prev_pictureid = pictureid;
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vp8->is_keyframe = !non_key;
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} else {
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uint16_t expected_seq = vp8->prev_seq + 1;
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if (!vp8->sequence_ok)
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return AVERROR(EAGAIN);
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if (vp8->timestamp != *timestamp) {
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// Missed the start of the new frame, sequence broken
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return vp8_broken_sequence(ctx, vp8,
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"Received no start marker; dropping frame\n");
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}
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if (seq != expected_seq) {
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if (vp8->is_keyframe) {
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return vp8_broken_sequence(ctx, vp8,
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"Missed part of a keyframe, sequence broken\n");
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} else if (vp8->data && avio_tell(vp8->data) >= vp8->first_part_size) {
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vp8->broken_frame = 1;
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vp8->sequence_dirty = 1;
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} else {
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return vp8_broken_sequence(ctx, vp8,
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"Missed part of the first partition, sequence broken\n");
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}
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}
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}
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if (!vp8->data)
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return vp8_broken_sequence(ctx, vp8, "Received no start marker\n");
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vp8->prev_seq = seq;
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if (!vp8->broken_frame)
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avio_write(vp8->data, buf, len);
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if (returned_old_frame) {
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*timestamp = old_timestamp;
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return end_packet ? 1 : 0;
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}
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if (end_packet) {
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int ret;
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ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
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if (ret < 0)
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return ret;
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if (vp8->sequence_dirty)
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pkt->flags |= AV_PKT_FLAG_CORRUPT;
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if (vp8->is_keyframe)
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pkt->flags |= AV_PKT_FLAG_KEY;
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return 0;
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}
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return AVERROR(EAGAIN);
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}
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static av_cold int vp8_init(AVFormatContext *s, int st_index, PayloadContext *vp8)
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{
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vp8->sequence_ok = 1;
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return 0;
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}
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static void vp8_close_context(PayloadContext *vp8)
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{
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ffio_free_dyn_buf(&vp8->data);
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}
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static int vp8_need_keyframe(PayloadContext *vp8)
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{
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return vp8->sequence_dirty || !vp8->sequence_ok;
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}
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const RTPDynamicProtocolHandler ff_vp8_dynamic_handler = {
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.enc_name = "VP8",
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.codec_type = AVMEDIA_TYPE_VIDEO,
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.codec_id = AV_CODEC_ID_VP8,
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.priv_data_size = sizeof(PayloadContext),
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.init = vp8_init,
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.close = vp8_close_context,
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.parse_packet = vp8_handle_packet,
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.need_keyframe = vp8_need_keyframe,
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};
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