mirror of
https://git.videolan.org/git/ffmpeg.git
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195 lines
6.3 KiB
C
195 lines
6.3 KiB
C
/*
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* RTP H.263 Depacketizer, RFC 2190
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* Copyright (c) 2012 Martin Storsjo
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* Based on the GStreamer H.263 Depayloder:
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* Copyright 2005 Wim Taymans
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* Copyright 2007 Edward Hervey
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* Copyright 2007 Nokia Corporation
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* Copyright 2007 Collabora Ltd, Philippe Kalaf
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* Copyright 2010 Mark Nauwelaerts
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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 "avformat.h"
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#include "avio_internal.h"
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#include "rtpdec_formats.h"
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#include "libavutil/attributes.h"
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#include "libavutil/intreadwrite.h"
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#include "libavcodec/get_bits.h"
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struct PayloadContext {
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AVIOContext *buf;
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uint8_t endbyte;
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int endbyte_bits;
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uint32_t timestamp;
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int newformat;
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};
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static void h263_close_context(PayloadContext *data)
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{
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ffio_free_dyn_buf(&data->buf);
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}
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static int h263_handle_packet(AVFormatContext *ctx, PayloadContext *data,
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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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/* Corresponding to header fields in the RFC */
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int f, p, i, sbit, ebit, src, r;
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int header_size, ret;
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if (data->newformat)
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return ff_h263_handle_packet(ctx, data, st, pkt, timestamp, buf, len,
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seq, flags);
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if (data->buf && data->timestamp != *timestamp) {
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/* Dropping old buffered, unfinished data */
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ffio_free_dyn_buf(&data->buf);
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data->endbyte_bits = 0;
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}
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if (len < 4) {
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av_log(ctx, AV_LOG_ERROR, "Too short H.263 RTP packet: %d\n", len);
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return AVERROR_INVALIDDATA;
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}
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f = buf[0] & 0x80;
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p = buf[0] & 0x40;
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if (!f) {
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/* Mode A */
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header_size = 4;
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i = buf[1] & 0x10;
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r = ((buf[1] & 0x01) << 3) | ((buf[2] & 0xe0) >> 5);
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} else if (!p) {
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/* Mode B */
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header_size = 8;
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if (len < header_size) {
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av_log(ctx, AV_LOG_ERROR,
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"Too short H.263 RTP packet: %d bytes, %d header bytes\n",
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len, header_size);
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return AVERROR_INVALIDDATA;
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}
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r = buf[3] & 0x03;
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i = buf[4] & 0x80;
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} else {
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/* Mode C */
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header_size = 12;
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if (len < header_size) {
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av_log(ctx, AV_LOG_ERROR,
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"Too short H.263 RTP packet: %d bytes, %d header bytes\n",
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len, header_size);
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return AVERROR_INVALIDDATA;
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}
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r = buf[3] & 0x03;
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i = buf[4] & 0x80;
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}
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sbit = (buf[0] >> 3) & 0x7;
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ebit = buf[0] & 0x7;
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src = (buf[1] & 0xe0) >> 5;
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if (!(buf[0] & 0xf8)) { /* Reserved bits in RFC 2429/4629 are zero */
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if ((src == 0 || src >= 6) && r) {
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/* Invalid src for this format, and bits that should be zero
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* according to RFC 2190 aren't zero. */
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av_log(ctx, AV_LOG_WARNING,
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"Interpreting H.263 RTP data as RFC 2429/4629 even though "
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"signalled with a static payload type.\n");
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data->newformat = 1;
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return ff_h263_handle_packet(ctx, data, st, pkt, timestamp, buf,
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len, seq, flags);
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}
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}
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buf += header_size;
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len -= header_size;
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if (!data->buf) {
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/* Check the picture start code, only start buffering a new frame
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* if this is correct */
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if (len > 4 && AV_RB32(buf) >> 10 == 0x20) {
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ret = avio_open_dyn_buf(&data->buf);
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if (ret < 0)
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return ret;
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data->timestamp = *timestamp;
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} else {
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/* Frame not started yet, skipping */
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return AVERROR(EAGAIN);
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}
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}
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if (data->endbyte_bits || sbit) {
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if (data->endbyte_bits == sbit) {
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data->endbyte |= buf[0] & (0xff >> sbit);
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data->endbyte_bits = 0;
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buf++;
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len--;
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avio_w8(data->buf, data->endbyte);
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} else {
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/* Start/end skip bits not matching - missed packets? */
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GetBitContext gb;
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init_get_bits(&gb, buf, len*8 - ebit);
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skip_bits(&gb, sbit);
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if (data->endbyte_bits) {
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data->endbyte |= get_bits(&gb, 8 - data->endbyte_bits);
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avio_w8(data->buf, data->endbyte);
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}
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while (get_bits_left(&gb) >= 8)
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avio_w8(data->buf, get_bits(&gb, 8));
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data->endbyte_bits = get_bits_left(&gb);
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if (data->endbyte_bits)
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data->endbyte = get_bits(&gb, data->endbyte_bits) <<
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(8 - data->endbyte_bits);
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ebit = 0;
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len = 0;
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}
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}
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if (ebit) {
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if (len > 0)
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avio_write(data->buf, buf, len - 1);
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data->endbyte_bits = 8 - ebit;
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data->endbyte = buf[len - 1] & (0xff << ebit);
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} else {
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avio_write(data->buf, buf, len);
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}
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if (!(flags & RTP_FLAG_MARKER))
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return AVERROR(EAGAIN);
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if (data->endbyte_bits)
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avio_w8(data->buf, data->endbyte);
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data->endbyte_bits = 0;
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ret = ff_rtp_finalize_packet(pkt, &data->buf, st->index);
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if (ret < 0)
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return ret;
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if (!i)
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pkt->flags |= AV_PKT_FLAG_KEY;
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return 0;
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}
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const RTPDynamicProtocolHandler ff_h263_rfc2190_dynamic_handler = {
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.codec_type = AVMEDIA_TYPE_VIDEO,
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.codec_id = AV_CODEC_ID_H263,
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.need_parsing = AVSTREAM_PARSE_FULL,
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.parse_packet = h263_handle_packet,
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.priv_data_size = sizeof(PayloadContext),
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.close = h263_close_context,
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.static_payload_id = 34,
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};
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