yading@11: /*
yading@11:  * RTP VP8 Depacketizer
yading@11:  * Copyright (c) 2010 Josh Allmann
yading@11:  * Copyright (c) 2012 Martin Storsjo
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: /**
yading@11:  * @file
yading@11:  * @brief RTP support for the VP8 payload
yading@11:  * @author Josh Allmann <joshua.allmann@gmail.com>
yading@11:  * @see http://tools.ietf.org/html/draft-ietf-payload-vp8-05
yading@11:  */
yading@11: 
yading@11: #include "libavcodec/bytestream.h"
yading@11: 
yading@11: #include "rtpdec_formats.h"
yading@11: 
yading@11: struct PayloadContext {
yading@11:     AVIOContext *data;
yading@11:     uint32_t     timestamp;
yading@11:     int          is_keyframe;
yading@11:     /* If sequence_ok is set, we keep returning data (even if we might have
yading@11:      * lost some data, but we haven't lost any too critical data that would
yading@11:      * cause the decoder to desynchronize and output random garbage).
yading@11:      */
yading@11:     int          sequence_ok;
yading@11:     int          first_part_size;
yading@11:     uint16_t     prev_seq;
yading@11:     int          prev_pictureid;
yading@11:     int          broken_frame;
yading@11:     /* If sequence_dirty is set, we have lost some data (critical or
yading@11:      * non-critical) and decoding will have some sort of artefacts, and
yading@11:      * we thus should request a new keyframe.
yading@11:      */
yading@11:     int          sequence_dirty;
yading@11:     int          got_keyframe;
yading@11: };
yading@11: 
yading@11: static void vp8_free_buffer(PayloadContext *vp8)
yading@11: {
yading@11:     uint8_t *tmp;
yading@11:     if (!vp8->data)
yading@11:         return;
yading@11:     avio_close_dyn_buf(vp8->data, &tmp);
yading@11:     av_free(tmp);
yading@11:     vp8->data = NULL;
yading@11: }
yading@11: 
yading@11: static int vp8_broken_sequence(AVFormatContext *ctx, PayloadContext *vp8,
yading@11:                                const char *msg)
yading@11: {
yading@11:     vp8->sequence_ok = 0;
yading@11:     av_log(ctx, AV_LOG_WARNING, "%s", msg);
yading@11:     vp8_free_buffer(vp8);
yading@11:     return AVERROR(EAGAIN);
yading@11: }
yading@11: 
yading@11: static int vp8_handle_packet(AVFormatContext *ctx, PayloadContext *vp8,
yading@11:                              AVStream *st, AVPacket *pkt, uint32_t *timestamp,
yading@11:                              const uint8_t *buf, int len, uint16_t seq,
yading@11:                              int flags)
yading@11: {
yading@11:     int start_partition, end_packet;
yading@11:     int extended_bits, part_id;
yading@11:     int pictureid_present = 0, tl0picidx_present = 0, tid_present = 0,
yading@11:         keyidx_present = 0;
yading@11:     int pictureid = -1, pictureid_mask = 0;
yading@11:     int returned_old_frame = 0;
yading@11:     uint32_t old_timestamp = 0;
yading@11: 
yading@11:     if (!buf) {
yading@11:         if (vp8->data) {
yading@11:             int ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
yading@11:             if (ret < 0)
yading@11:                 return ret;
yading@11:             *timestamp = vp8->timestamp;
yading@11:             if (vp8->sequence_dirty)
yading@11:                 pkt->flags |= AV_PKT_FLAG_CORRUPT;
yading@11:             return 0;
yading@11:         }
yading@11:         return AVERROR(EAGAIN);
yading@11:     }
yading@11: 
yading@11:     if (len < 1)
yading@11:         return AVERROR_INVALIDDATA;
yading@11: 
yading@11:     extended_bits   = buf[0] & 0x80;
yading@11:     start_partition = buf[0] & 0x10;
yading@11:     part_id         = buf[0] & 0x0f;
yading@11:     end_packet      = flags & RTP_FLAG_MARKER;
yading@11:     buf++;
yading@11:     len--;
yading@11:     if (extended_bits) {
yading@11:         if (len < 1)
yading@11:             return AVERROR_INVALIDDATA;
yading@11:         pictureid_present = buf[0] & 0x80;
yading@11:         tl0picidx_present = buf[0] & 0x40;
yading@11:         tid_present       = buf[0] & 0x20;
yading@11:         keyidx_present    = buf[0] & 0x10;
yading@11:         buf++;
yading@11:         len--;
yading@11:     }
yading@11:     if (pictureid_present) {
yading@11:         if (len < 1)
yading@11:             return AVERROR_INVALIDDATA;
yading@11:         if (buf[0] & 0x80) {
yading@11:             if (len < 2)
yading@11:                 return AVERROR_INVALIDDATA;
yading@11:             pictureid = AV_RB16(buf) & 0x7fff;
yading@11:             pictureid_mask = 0x7fff;
yading@11:             buf += 2;
yading@11:             len -= 2;
yading@11:         } else {
yading@11:             pictureid = buf[0] & 0x7f;
yading@11:             pictureid_mask = 0x7f;
yading@11:             buf++;
yading@11:             len--;
yading@11:         }
yading@11:     }
yading@11:     if (tl0picidx_present) {
yading@11:         // Ignoring temporal level zero index
yading@11:         buf++;
yading@11:         len--;
yading@11:     }
yading@11:     if (tid_present || keyidx_present) {
yading@11:         // Ignoring temporal layer index, layer sync bit and keyframe index
yading@11:         buf++;
yading@11:         len--;
yading@11:     }
yading@11:     if (len < 1)
yading@11:         return AVERROR_INVALIDDATA;
yading@11: 
yading@11:     if (start_partition && part_id == 0 && len >= 3) {
yading@11:         int res;
yading@11:         int non_key = buf[0] & 0x01;
yading@11:         if (!non_key) {
yading@11:             vp8_free_buffer(vp8);
yading@11:             // Keyframe, decoding ok again
yading@11:             vp8->sequence_ok = 1;
yading@11:             vp8->sequence_dirty = 0;
yading@11:             vp8->got_keyframe = 1;
yading@11:         } else {
yading@11:             int can_continue = vp8->data && !vp8->is_keyframe &&
yading@11:                                avio_tell(vp8->data) >= vp8->first_part_size;
yading@11:             if (!vp8->sequence_ok)
yading@11:                 return AVERROR(EAGAIN);
yading@11:             if (!vp8->got_keyframe)
yading@11:                 return vp8_broken_sequence(ctx, vp8, "Keyframe missing\n");
yading@11:             if (pictureid >= 0) {
yading@11:                 if (pictureid != ((vp8->prev_pictureid + 1) & pictureid_mask)) {
yading@11:                     return vp8_broken_sequence(ctx, vp8,
yading@11:                                                "Missed a picture, sequence broken\n");
yading@11:                 } else {
yading@11:                     if (vp8->data && !can_continue)
yading@11:                         return vp8_broken_sequence(ctx, vp8,
yading@11:                                                    "Missed a picture, sequence broken\n");
yading@11:                 }
yading@11:             } else {
yading@11:                 uint16_t expected_seq = vp8->prev_seq + 1;
yading@11:                 int16_t diff = seq - expected_seq;
yading@11:                 if (vp8->data) {
yading@11:                     // No picture id, so we can't know if missed packets
yading@11:                     // contained any new frames. If diff == 0, we did get
yading@11:                     // later packets from the same frame (matching timestamp),
yading@11:                     // so we know we didn't miss any frame. If diff == 1 and
yading@11:                     // we still have data (not flushed by the end of frame
yading@11:                     // marker), the single missed packet must have been part
yading@11:                     // of the same frame.
yading@11:                     if ((diff == 0 || diff == 1) && can_continue) {
yading@11:                         // Proceed with what we have
yading@11:                     } else {
yading@11:                         return vp8_broken_sequence(ctx, vp8,
yading@11:                                                    "Missed too much, sequence broken\n");
yading@11:                     }
yading@11:                 } else {
yading@11:                     if (diff != 0)
yading@11:                         return vp8_broken_sequence(ctx, vp8,
yading@11:                                                    "Missed unknown data, sequence broken\n");
yading@11:                 }
yading@11:             }
yading@11:             if (vp8->data) {
yading@11:                 vp8->sequence_dirty = 1;
yading@11:                 if (avio_tell(vp8->data) >= vp8->first_part_size) {
yading@11:                     int ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
yading@11:                     if (ret < 0)
yading@11:                         return ret;
yading@11:                     pkt->flags |= AV_PKT_FLAG_CORRUPT;
yading@11:                     returned_old_frame = 1;
yading@11:                     old_timestamp = vp8->timestamp;
yading@11:                 } else {
yading@11:                     // Shouldn't happen
yading@11:                     vp8_free_buffer(vp8);
yading@11:                 }
yading@11:             }
yading@11:         }
yading@11:         vp8->first_part_size = (AV_RL16(&buf[1]) << 3 | buf[0] >> 5) + 3;
yading@11:         if ((res = avio_open_dyn_buf(&vp8->data)) < 0)
yading@11:             return res;
yading@11:         vp8->timestamp = *timestamp;
yading@11:         vp8->broken_frame = 0;
yading@11:         vp8->prev_pictureid = pictureid;
yading@11:         vp8->is_keyframe = !non_key;
yading@11:     } else {
yading@11:         uint16_t expected_seq = vp8->prev_seq + 1;
yading@11: 
yading@11:         if (!vp8->sequence_ok)
yading@11:             return AVERROR(EAGAIN);
yading@11: 
yading@11:         if (vp8->timestamp != *timestamp) {
yading@11:             // Missed the start of the new frame, sequence broken
yading@11:             return vp8_broken_sequence(ctx, vp8,
yading@11:                                        "Received no start marker; dropping frame\n");
yading@11:         }
yading@11: 
yading@11:         if (seq != expected_seq) {
yading@11:             if (vp8->is_keyframe) {
yading@11:                 return vp8_broken_sequence(ctx, vp8,
yading@11:                                            "Missed part of a keyframe, sequence broken\n");
yading@11:             } else if (vp8->data && avio_tell(vp8->data) >= vp8->first_part_size) {
yading@11:                 vp8->broken_frame = 1;
yading@11:                 vp8->sequence_dirty = 1;
yading@11:             } else {
yading@11:                 return vp8_broken_sequence(ctx, vp8,
yading@11:                                            "Missed part of the first partition, sequence broken\n");
yading@11:             }
yading@11:         }
yading@11:     }
yading@11: 
yading@11:     if (!vp8->data)
yading@11:         return vp8_broken_sequence(ctx, vp8, "Received no start marker\n");
yading@11: 
yading@11:     vp8->prev_seq = seq;
yading@11:     if (!vp8->broken_frame)
yading@11:         avio_write(vp8->data, buf, len);
yading@11: 
yading@11:     if (returned_old_frame) {
yading@11:         *timestamp = old_timestamp;
yading@11:         return end_packet ? 1 : 0;
yading@11:     }
yading@11: 
yading@11:     if (end_packet) {
yading@11:         int ret;
yading@11:         ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
yading@11:         if (ret < 0)
yading@11:             return ret;
yading@11:         if (vp8->sequence_dirty)
yading@11:             pkt->flags |= AV_PKT_FLAG_CORRUPT;
yading@11:         return 0;
yading@11:     }
yading@11: 
yading@11:     return AVERROR(EAGAIN);
yading@11: }
yading@11: 
yading@11: static PayloadContext *vp8_new_context(void)
yading@11: {
yading@11:     PayloadContext *vp8 = av_mallocz(sizeof(PayloadContext));
yading@11:     if (!vp8)
yading@11:         return NULL;
yading@11:     vp8->sequence_ok = 1;
yading@11:     return vp8;
yading@11: }
yading@11: 
yading@11: static void vp8_free_context(PayloadContext *vp8)
yading@11: {
yading@11:     vp8_free_buffer(vp8);
yading@11:     av_free(vp8);
yading@11: }
yading@11: 
yading@11: static int vp8_need_keyframe(PayloadContext *vp8)
yading@11: {
yading@11:     return vp8->sequence_dirty || !vp8->sequence_ok;
yading@11: }
yading@11: 
yading@11: RTPDynamicProtocolHandler ff_vp8_dynamic_handler = {
yading@11:     .enc_name       = "VP8",
yading@11:     .codec_type     = AVMEDIA_TYPE_VIDEO,
yading@11:     .codec_id       = AV_CODEC_ID_VP8,
yading@11:     .alloc          = vp8_new_context,
yading@11:     .free           = vp8_free_context,
yading@11:     .parse_packet   = vp8_handle_packet,
yading@11:     .need_keyframe  = vp8_need_keyframe,
yading@11: };