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/*
* RTP H.263 Depacketizer, RFC 2190
* Copyright (c) 2012 Martin Storsjo
* Based on the GStreamer H.263 Depayloder:
* Copyright 2005 Wim Taymans
* Copyright 2007 Edward Hervey
* Copyright 2007 Nokia Corporation
* Copyright 2007 Collabora Ltd, Philippe Kalaf
* Copyright 2010 Mark Nauwelaerts
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avformat.h"
#include "rtpdec_formats.h"
#include "libavutil/intreadwrite.h"
#include "libavcodec/get_bits.h"
struct PayloadContext {
AVIOContext *buf;
uint8_t endbyte;
int endbyte_bits;
uint32_t timestamp;
};
static PayloadContext *h263_new_context(void)
{
return av_mallocz(sizeof(PayloadContext));
}
static void h263_free_context(PayloadContext *data)
{
if (!data)
return;
if (data->buf) {
uint8_t *p;
avio_close_dyn_buf(data->buf, &p);
av_free(p);
}
av_free(data);
}
static int h263_handle_packet(AVFormatContext *ctx, PayloadContext *data,
AVStream *st, AVPacket *pkt, uint32_t *timestamp,
const uint8_t *buf, int len, int flags)
{
int f, p, i, sbit, ebit; /* Corresponding to header fields in the RFC */
int header_size;
if (data->buf && data->timestamp != *timestamp) {
/* Dropping old buffered, unfinished data */
uint8_t *p;
avio_close_dyn_buf(data->buf, &p);
av_free(p);
data->buf = NULL;
}
if (len < 4) {
av_log(ctx, AV_LOG_ERROR, "Too short H.263 RTP packet: %d\n", len);
return AVERROR_INVALIDDATA;
}
f = buf[0] & 0x80;
p = buf[0] & 0x40;
if (!f) {
/* Mode A */
header_size = 4;
i = buf[1] & 0x10;
} else if (!p) {
/* Mode B */
header_size = 8;
if (len < header_size) {
av_log(ctx, AV_LOG_ERROR,
"Too short H.263 RTP packet: %d bytes, %d header bytes\n",
len, header_size);
return AVERROR_INVALIDDATA;
}
i = buf[4] & 0x80;
} else {
/* Mode C */
header_size = 12;
if (len < header_size) {
av_log(ctx, AV_LOG_ERROR,
"Too short H.263 RTP packet: %d bytes, %d header bytes\n",
len, header_size);
return AVERROR_INVALIDDATA;
}
i = buf[4] & 0x80;
}
sbit = (buf[0] >> 3) & 0x7;
ebit = buf[0] & 0x7;
buf += header_size;
len -= header_size;
if (!data->buf) {
/* Check the picture start code, only start buffering a new frame
* if this is correct */
if (!f && len > 4 && AV_RB32(buf) >> 10 == 0x20) {
int ret = avio_open_dyn_buf(&data->buf);
if (ret < 0)
return ret;
data->timestamp = *timestamp;
} else {
/* Frame not started yet, skipping */
return AVERROR(EAGAIN);
}
}
if (data->endbyte_bits || sbit) {
if (data->endbyte_bits == sbit) {
data->endbyte |= buf[0] & (0xff >> sbit);
data->endbyte_bits = 0;
buf++;
len--;
avio_w8(data->buf, data->endbyte);
} else {
/* Start/end skip bits not matching - missed packets? */
GetBitContext gb;
init_get_bits(&gb, buf, len*8 - ebit);
skip_bits(&gb, sbit);
if (data->endbyte_bits) {
data->endbyte |= get_bits(&gb, 8 - data->endbyte_bits);
avio_w8(data->buf, data->endbyte);
}
while (get_bits_left(&gb) >= 8)
avio_w8(data->buf, get_bits(&gb, 8));
data->endbyte_bits = get_bits_left(&gb);
if (data->endbyte_bits)
data->endbyte = get_bits(&gb, data->endbyte_bits) <<
(8 - data->endbyte_bits);
ebit = 0;
len = 0;
}
}
if (ebit) {
if (len > 0)
avio_write(data->buf, buf, len - 1);
data->endbyte_bits = 8 - ebit;
data->endbyte = buf[len - 1] & (0xff << ebit);
} else {
avio_write(data->buf, buf, len);
}
if (!(flags & RTP_FLAG_MARKER))
return AVERROR(EAGAIN);
if (data->endbyte_bits)
avio_w8(data->buf, data->endbyte);
data->endbyte_bits = 0;
av_init_packet(pkt);
pkt->size = avio_close_dyn_buf(data->buf, &pkt->data);
pkt->destruct = av_destruct_packet;
pkt->stream_index = st->index;
if (!i)
pkt->flags |= AV_PKT_FLAG_KEY;
data->buf = NULL;
return 0;
}
RTPDynamicProtocolHandler ff_h263_rfc2190_dynamic_handler = {
.codec_type = AVMEDIA_TYPE_VIDEO,
.codec_id = CODEC_ID_H263,
.parse_packet = h263_handle_packet,
.alloc = h263_new_context,
.free = h263_free_context,
.static_payload_id = 34,
};
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