342 lines
11 KiB
C
342 lines
11 KiB
C
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/*
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* RTP parser for VP9 payload format (draft version 02) - experimental
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* Copyright (c) 2015 Thomas Volkert <thomas@homer-conferencing.com>
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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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#include "libavutil/intreadwrite.h"
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#include "avio_internal.h"
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#include "rtpdec_formats.h"
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#define RTP_VP9_DESC_REQUIRED_SIZE 1
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struct PayloadContext {
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AVIOContext *buf;
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uint32_t timestamp;
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};
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static av_cold int vp9_init(AVFormatContext *ctx, int st_index,
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PayloadContext *data)
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{
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av_log(ctx, AV_LOG_WARNING,
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"RTP/VP9 support is still experimental\n");
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return 0;
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}
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static int vp9_handle_packet(AVFormatContext *ctx, PayloadContext *rtp_vp9_ctx,
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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 has_pic_id, has_layer_idc, has_ref_idc, has_ss_data;
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av_unused int pic_id = 0, non_key_frame = 0, inter_picture_layer_frame;
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av_unused int layer_temporal = -1, layer_spatial = -1, layer_quality = -1;
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int ref_fields = 0, has_ref_field_ext_pic_id = 0;
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int first_fragment, last_fragment;
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int rtp_m;
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int res = 0;
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/* drop data of previous packets in case of non-continuous (lossy) packet stream */
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if (rtp_vp9_ctx->buf && rtp_vp9_ctx->timestamp != *timestamp)
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ffio_free_dyn_buf(&rtp_vp9_ctx->buf);
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/* sanity check for size of input packet: 1 byte payload at least */
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if (len < RTP_VP9_DESC_REQUIRED_SIZE + 1) {
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av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet, got %d bytes\n", len);
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return AVERROR_INVALIDDATA;
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}
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/*
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* decode the required VP9 payload descriptor according to section 4.2 of the spec.:
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*
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* 0 1 2 3 4 5 6 7
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* +-+-+-+-+-+-+-+-+
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* |I|P|L|F|B|E|V|-| (REQUIRED)
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* +-+-+-+-+-+-+-+-+
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*
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* I: PictureID present
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* P: Inter-picture predicted layer frame
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* L: Layer indices present
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* F: Flexible mode
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* B: Start of VP9 frame
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* E: End of picture
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* V: Scalability Structure (SS) present
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*/
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has_pic_id = !!(buf[0] & 0x80);
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inter_picture_layer_frame = !!(buf[0] & 0x40);
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has_layer_idc = !!(buf[0] & 0x20);
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has_ref_idc = !!(buf[0] & 0x10);
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first_fragment = !!(buf[0] & 0x08);
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last_fragment = !!(buf[0] & 0x04);
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has_ss_data = !!(buf[0] & 0x02);
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rtp_m = !!(flags & RTP_FLAG_MARKER);
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/* sanity check for markers: B should always be equal to the RTP M marker */
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if (last_fragment != rtp_m) {
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av_log(ctx, AV_LOG_ERROR, "Invalid combination of B and M marker (%d != %d)\n", last_fragment, rtp_m);
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return AVERROR_INVALIDDATA;
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}
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/* pass the extensions field */
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buf += RTP_VP9_DESC_REQUIRED_SIZE;
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len -= RTP_VP9_DESC_REQUIRED_SIZE;
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/*
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* decode the 1-byte/2-byte picture ID:
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*
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* 0 1 2 3 4 5 6 7
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* +-+-+-+-+-+-+-+-+
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* I: |M|PICTURE ID | (RECOMMENDED)
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* +-+-+-+-+-+-+-+-+
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* M: | EXTENDED PID | (RECOMMENDED)
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* +-+-+-+-+-+-+-+-+
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*
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* M: The most significant bit of the first octet is an extension flag.
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* PictureID: 8 or 16 bits including the M bit.
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*/
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if (has_pic_id) {
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/* check for 1-byte or 2-byte picture index */
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if (buf[0] & 0x80) {
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if (len < 2) {
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av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
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return AVERROR_INVALIDDATA;
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}
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pic_id = AV_RB16(buf) & 0x7fff;
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buf += 2;
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len -= 2;
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} else {
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pic_id = buf[0] & 0x7f;
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buf++;
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len--;
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}
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}
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/*
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* decode layer indices
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*
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* 0 1 2 3 4 5 6 7
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* +-+-+-+-+-+-+-+-+
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* L: | T | S | Q | R | (CONDITIONALLY RECOMMENDED)
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* +-+-+-+-+-+-+-+-+
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*
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* T, S and Q are 2-bit indices for temporal, spatial, and quality layers.
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* If "F" is set in the initial octet, R is 2 bits representing the number
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* of reference fields this frame refers to.
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*/
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if (has_layer_idc) {
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if (len < 1) {
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av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
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return AVERROR_INVALIDDATA;
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}
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layer_temporal = buf[0] & 0xC0;
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layer_spatial = buf[0] & 0x30;
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layer_quality = buf[0] & 0x0C;
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if (has_ref_idc) {
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ref_fields = buf[0] & 0x03;
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if (ref_fields)
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non_key_frame = 1;
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}
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buf++;
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len--;
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}
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/*
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* decode the reference fields
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*
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* 0 1 2 3 4 5 6 7
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* +-+-+-+-+-+-+-+-+ -\
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* F: | PID |X| RS| RQ| (OPTIONAL) .
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* +-+-+-+-+-+-+-+-+ . - R times
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* X: | EXTENDED PID | (OPTIONAL) .
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* +-+-+-+-+-+-+-+-+ -/
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*
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* PID: The relative Picture ID referred to by this frame.
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* RS and RQ: The spatial and quality layer IDs.
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* X: 1 if this layer index has an extended relative Picture ID.
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*/
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if (has_ref_idc) {
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while (ref_fields) {
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if (len < 1) {
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av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
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return AVERROR_INVALIDDATA;
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}
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has_ref_field_ext_pic_id = buf[0] & 0x10;
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/* pass ref. field */
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if (has_ref_field_ext_pic_id) {
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if (len < 2) {
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av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
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return AVERROR_INVALIDDATA;
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}
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/* ignore ref. data */
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buf += 2;
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len -= 2;
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} else {
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/* ignore ref. data */
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buf++;
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len--;
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}
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ref_fields--;
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}
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}
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/*
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* decode the scalability structure (SS)
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*
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* 0 1 2 3 4 5 6 7
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* +-+-+-+-+-+-+-+-+
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* V: | PATTERN LENGTH|
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* +-+-+-+-+-+-+-+-+ -\
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* | T | S | Q | R | (OPTIONAL) .
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* +-+-+-+-+-+-+-+-+ -\ .
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* | PID |X| RS| RQ| (OPTIONAL) . . - PAT. LEN. times
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* +-+-+-+-+-+-+-+-+ . - R times .
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* X: | EXTENDED PID | (OPTIONAL) . .
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* +-+-+-+-+-+-+-+-+ -/ -/
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*
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* PID: The relative Picture ID referred to by this frame.
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* RS and RQ: The spatial and quality layer IDs.
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* X: 1 if this layer index has an extended relative Picture ID.
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*/
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if (has_ss_data) {
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int n_s, y, g, i;
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if (len < 1) {
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av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
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return AVERROR_INVALIDDATA;
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}
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n_s = buf[0] >> 5;
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y = !!(buf[0] & 0x10);
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g = !!(buf[0] & 0x08);
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buf++;
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len--;
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if (n_s > 0) {
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avpriv_report_missing_feature(ctx, "VP9 scalability structure with multiple layers");
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return AVERROR_PATCHWELCOME;
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}
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if (y) {
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if (len < 4 * (n_s + 1)) {
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av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
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return AVERROR_INVALIDDATA;
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}
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for (i = 0; i < n_s + 1; i++) {
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av_unused int w, h;
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w = AV_RB16(buf);
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h = AV_RB16(buf + 2);
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buf += 4;
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len -= 4;
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}
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}
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if (g) {
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int n_g;
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if (len < 1) {
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av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
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return AVERROR_INVALIDDATA;
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}
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n_g = buf[0];
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buf++;
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len--;
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for (i = 0; i < n_g; i++) {
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av_unused int t, u, r, j;
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if (len < 1) {
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av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
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return AVERROR_INVALIDDATA;
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}
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t = buf[0] >> 5;
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u = !!(buf[0] & 0x10);
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r = (buf[0] >> 2) & 0x03;
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buf++;
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len--;
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if (len < r) {
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av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
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return AVERROR_INVALIDDATA;
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}
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for (j = 0; j < r; j++) {
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av_unused int p_diff = buf[0];
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buf++;
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len--;
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}
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}
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}
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}
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/*
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* decode the VP9 payload header
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*
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* spec. is tbd
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*/
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//XXX: implement when specified
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/* sanity check: 1 byte payload as minimum */
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if (len < 1) {
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av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
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return AVERROR_INVALIDDATA;
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}
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/* start frame buffering with new dynamic buffer */
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if (!rtp_vp9_ctx->buf) {
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/* sanity check: a new frame should have started */
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if (first_fragment) {
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res = avio_open_dyn_buf(&rtp_vp9_ctx->buf);
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if (res < 0)
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return res;
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/* update the timestamp in the frame packet with the one from the RTP packet */
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rtp_vp9_ctx->timestamp = *timestamp;
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} else {
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/* frame not started yet, need more packets */
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return AVERROR(EAGAIN);
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}
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}
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/* write the fragment to the dyn. buffer */
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avio_write(rtp_vp9_ctx->buf, buf, len);
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/* do we need more fragments? */
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if (!last_fragment)
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return AVERROR(EAGAIN);
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/* close frame buffering and create resulting A/V packet */
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res = ff_rtp_finalize_packet(pkt, &rtp_vp9_ctx->buf, st->index);
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if (res < 0)
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return res;
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return 0;
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}
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static void vp9_close_context(PayloadContext *vp9)
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{
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ffio_free_dyn_buf(&vp9->buf);
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}
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const RTPDynamicProtocolHandler ff_vp9_dynamic_handler = {
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.enc_name = "VP9",
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.codec_type = AVMEDIA_TYPE_VIDEO,
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.codec_id = AV_CODEC_ID_VP9,
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.priv_data_size = sizeof(PayloadContext),
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.init = vp9_init,
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.close = vp9_close_context,
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.parse_packet = vp9_handle_packet
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};
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