/* * RTP VP8 Depacketizer * Copyright (c) 2010 Josh Allmann * Copyright (c) 2012 Martin Storsjo * * 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 */ /** * @file * @brief RTP support for the VP8 payload * @author Josh Allmann <joshua.allmann@gmail.com> * @see http://tools.ietf.org/html/draft-ietf-payload-vp8-05 */ #include "libavcodec/bytestream.h" #include "avio_internal.h" #include "rtpdec_formats.h" struct PayloadContext { AVIOContext *data; uint32_t timestamp; int is_keyframe; /* If sequence_ok is set, we keep returning data (even if we might have * lost some data, but we haven't lost any too critical data that would * cause the decoder to desynchronize and output random garbage). */ int sequence_ok; int first_part_size; uint16_t prev_seq; int prev_pictureid; int broken_frame; /* If sequence_dirty is set, we have lost some data (critical or * non-critical) and decoding will have some sort of artifacts, and * we thus should request a new keyframe. */ int sequence_dirty; int got_keyframe; }; static int vp8_broken_sequence(AVFormatContext *ctx, PayloadContext *vp8, const char *msg) { vp8->sequence_ok = 0; av_log(ctx, AV_LOG_WARNING, "%s", msg); ffio_free_dyn_buf(&vp8->data); return AVERROR(EAGAIN); } static int vp8_handle_packet(AVFormatContext *ctx, PayloadContext *vp8, AVStream *st, AVPacket *pkt, uint32_t *timestamp, const uint8_t *buf, int len, uint16_t seq, int flags) { int start_partition, end_packet; int extended_bits, part_id; int pictureid_present = 0, tl0picidx_present = 0, tid_present = 0, keyidx_present = 0; int pictureid = -1, pictureid_mask = 0; int returned_old_frame = 0; uint32_t old_timestamp = 0; if (!buf) { if (vp8->data) { int ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index); if (ret < 0) return ret; *timestamp = vp8->timestamp; if (vp8->sequence_dirty) pkt->flags |= AV_PKT_FLAG_CORRUPT; return 0; } return AVERROR(EAGAIN); } if (len < 1) return AVERROR_INVALIDDATA; extended_bits = buf[0] & 0x80; 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; pictureid_mask = 0x7fff; buf += 2; len -= 2; } else { pictureid = buf[0] & 0x7f; pictureid_mask = 0x7f; buf++; len--; } } if (tl0picidx_present) { // Ignoring temporal level zero index buf++; len--; } if (tid_present || keyidx_present) { // Ignoring temporal layer index, layer sync bit and keyframe index buf++; len--; } if (len < 1) return AVERROR_INVALIDDATA; if (start_partition && part_id == 0 && len >= 3) { int res; int non_key = buf[0] & 0x01; if (!non_key) { ffio_free_dyn_buf(&vp8->data); // Keyframe, decoding ok again vp8->sequence_ok = 1; vp8->sequence_dirty = 0; vp8->got_keyframe = 1; } else { int can_continue = vp8->data && !vp8->is_keyframe && avio_tell(vp8->data) >= vp8->first_part_size; if (!vp8->sequence_ok) return AVERROR(EAGAIN); if (!vp8->got_keyframe) return vp8_broken_sequence(ctx, vp8, "Keyframe missing\n"); if (pictureid >= 0) { if (pictureid != ((vp8->prev_pictureid + 1) & pictureid_mask)) { return vp8_broken_sequence(ctx, vp8, "Missed a picture, sequence broken\n"); } else { if (vp8->data && !can_continue) return vp8_broken_sequence(ctx, vp8, "Missed a picture, sequence broken\n"); } } else { uint16_t expected_seq = vp8->prev_seq + 1; int16_t diff = seq - expected_seq; if (vp8->data) { // No picture id, so we can't know if missed packets // contained any new frames. If diff == 0, we did get // later packets from the same frame (matching timestamp), // so we know we didn't miss any frame. If diff == 1 and // we still have data (not flushed by the end of frame // marker), the single missed packet must have been part // of the same frame. if ((diff == 0 || diff == 1) && can_continue) { // Proceed with what we have } else { return vp8_broken_sequence(ctx, vp8, "Missed too much, sequence broken\n"); } } else { if (diff != 0) return vp8_broken_sequence(ctx, vp8, "Missed unknown data, sequence broken\n"); } } if (vp8->data) { vp8->sequence_dirty = 1; if (avio_tell(vp8->data) >= vp8->first_part_size) { int ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index); if (ret < 0) return ret; pkt->flags |= AV_PKT_FLAG_CORRUPT; returned_old_frame = 1; old_timestamp = vp8->timestamp; } else { // Shouldn't happen ffio_free_dyn_buf(&vp8->data); } } } vp8->first_part_size = (AV_RL16(&buf[1]) << 3 | buf[0] >> 5) + 3; if ((res = avio_open_dyn_buf(&vp8->data)) < 0) return res; vp8->timestamp = *timestamp; vp8->broken_frame = 0; vp8->prev_pictureid = pictureid; vp8->is_keyframe = !non_key; } else { uint16_t expected_seq = vp8->prev_seq + 1; if (!vp8->sequence_ok) return AVERROR(EAGAIN); if (vp8->timestamp != *timestamp) { // Missed the start of the new frame, sequence broken return vp8_broken_sequence(ctx, vp8, "Received no start marker; dropping frame\n"); } if (seq != expected_seq) { if (vp8->is_keyframe) { return vp8_broken_sequence(ctx, vp8, "Missed part of a keyframe, sequence broken\n"); } else if (vp8->data && avio_tell(vp8->data) >= vp8->first_part_size) { vp8->broken_frame = 1; vp8->sequence_dirty = 1; } else { return vp8_broken_sequence(ctx, vp8, "Missed part of the first partition, sequence broken\n"); } } } if (!vp8->data) return vp8_broken_sequence(ctx, vp8, "Received no start marker\n"); vp8->prev_seq = seq; if (!vp8->broken_frame) avio_write(vp8->data, buf, len); if (returned_old_frame) { *timestamp = old_timestamp; return end_packet ? 1 : 0; } if (end_packet) { int ret; ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index); if (ret < 0) return ret; if (vp8->sequence_dirty) pkt->flags |= AV_PKT_FLAG_CORRUPT; if (vp8->is_keyframe) pkt->flags |= AV_PKT_FLAG_KEY; return 0; } return AVERROR(EAGAIN); } static av_cold int vp8_init(AVFormatContext *s, int st_index, PayloadContext *vp8) { vp8->sequence_ok = 1; return 0; } static void vp8_close_context(PayloadContext *vp8) { ffio_free_dyn_buf(&vp8->data); } static int vp8_need_keyframe(PayloadContext *vp8) { return vp8->sequence_dirty || !vp8->sequence_ok; } const RTPDynamicProtocolHandler ff_vp8_dynamic_handler = { .enc_name = "VP8", .codec_type = AVMEDIA_TYPE_VIDEO, .codec_id = AV_CODEC_ID_VP8, .priv_data_size = sizeof(PayloadContext), .init = vp8_init, .close = vp8_close_context, .parse_packet = vp8_handle_packet, .need_keyframe = vp8_need_keyframe, };