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FFmpeg/libavformat/rtpdec_qt.c
Andreas Rheinhardt 7001ff74ba avformat/aviobuf: Add ffio_init_(read|write)_context() 
Most users of ffio_init_context() simply want to wrap
a buffer into an AVIOContext; they do not provide
function pointers at all.

Therefore this commit adds shortcuts for these two common
operations. This also allows to accept const data when reading
(i.e. the const is now cast away at a central place in
ffio_init_read_context() instead of at several callers).
This also allows to constify the data in ff_text_init_buf().

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2023-09-07 00:41:45 +02:00

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/*
* RTP/Quicktime support.
* Copyright (c) 2009 Ronald S. Bultje
*
* 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 Quicktime-style RTP support
* @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>
*/
#include "avformat.h"
#include "internal.h"
#include "avio_internal.h"
#include "rtp.h"
#include "rtpdec.h"
#include "isom.h"
#include "libavcodec/get_bits.h"
struct PayloadContext {
AVPacket *pkt;
int bytes_per_frame, remaining;
uint32_t timestamp;
};
static av_cold int qt_rtp_init(AVFormatContext *ctx, int st_index,
PayloadContext *qt)
{
qt->pkt = av_packet_alloc();
if (!qt->pkt)
return AVERROR(ENOMEM);
return 0;
}
static int qt_rtp_parse_packet(AVFormatContext *s, PayloadContext *qt,
AVStream *st, AVPacket *pkt,
uint32_t *timestamp, const uint8_t *buf,
int len, uint16_t seq, int flags)
{
FFIOContext pb0;
AVIOContext *const pb = &pb0.pub;
GetBitContext gb;
int packing_scheme, has_payload_desc, has_packet_info, alen,
has_marker_bit = flags & RTP_FLAG_MARKER,
keyframe, ret;
if (qt->remaining) {
int num = qt->pkt->size / qt->bytes_per_frame;
if ((ret = av_new_packet(pkt, qt->bytes_per_frame)) < 0)
return ret;
pkt->stream_index = st->index;
pkt->flags = qt->pkt->flags;
memcpy(pkt->data,
&qt->pkt->data[(num - qt->remaining) * qt->bytes_per_frame],
qt->bytes_per_frame);
if (--qt->remaining == 0) {
av_freep(&qt->pkt->data);
qt->pkt->size = 0;
}
return qt->remaining > 0;
}
/**
* The RTP payload is described in:
* http://developer.apple.com/quicktime/icefloe/dispatch026.html
*/
ret = init_get_bits(&gb, buf, len << 3);
if (ret < 0)
return ret;
ffio_init_read_context(&pb0, buf, len);
if (len < 4)
return AVERROR_INVALIDDATA;
skip_bits(&gb, 4); // version
if ((packing_scheme = get_bits(&gb, 2)) == 0)
return AVERROR_INVALIDDATA;
keyframe = get_bits1(&gb);
has_payload_desc = get_bits1(&gb);
has_packet_info = get_bits1(&gb);
skip_bits(&gb, 23); // reserved:7, cache payload info:1, payload ID:15
if (has_payload_desc) {
int data_len, pos, is_start, is_finish;
uint32_t tag;
pos = get_bits_count(&gb) >> 3;
if (pos + 12 > len)
return AVERROR_INVALIDDATA;
skip_bits(&gb, 2); // has non-I-frames:1, is sparse:1
is_start = get_bits1(&gb);
is_finish = get_bits1(&gb);
if (!is_start || !is_finish) {
avpriv_request_sample(s, "RTP-X-QT with payload description "
"split over several packets");
return AVERROR_PATCHWELCOME;
}
skip_bits(&gb, 12); // reserved
data_len = get_bits(&gb, 16);
avio_seek(pb, pos + 4, SEEK_SET);
tag = avio_rl32(pb);
if ((st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
tag != MKTAG('v','i','d','e')) ||
(st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&
tag != MKTAG('s','o','u','n')))
return AVERROR_INVALIDDATA;
avpriv_set_pts_info(st, 32, 1, avio_rb32(pb));
if (pos + data_len > len)
return AVERROR_INVALIDDATA;
/* TLVs */
while (avio_tell(pb) + 4 < pos + data_len) {
int tlv_len = avio_rb16(pb);
tag = avio_rl16(pb);
if (avio_tell(pb) + tlv_len > pos + data_len)
return AVERROR_INVALIDDATA;
#define MKTAG16(a,b) MKTAG(a,b,0,0)
switch (tag) {
case MKTAG16('s','d'): {
MOVStreamContext *msc;
void *priv_data = st->priv_data;
int nb_streams = s->nb_streams;
MOVContext *mc = av_mallocz(sizeof(*mc));
if (!mc)
return AVERROR(ENOMEM);
mc->fc = s;
st->priv_data = msc = av_mallocz(sizeof(MOVStreamContext));
if (!msc) {
av_free(mc);
st->priv_data = priv_data;
return AVERROR(ENOMEM);
}
/* ff_mov_read_stsd_entries updates stream s->nb_streams-1,
* so set it temporarily to indicate which stream to update. */
s->nb_streams = st->index + 1;
ff_mov_read_stsd_entries(mc, pb, 1);
qt->bytes_per_frame = msc->bytes_per_frame;
av_free(msc);
av_free(mc);
st->priv_data = priv_data;
s->nb_streams = nb_streams;
break;
}
default:
avio_skip(pb, tlv_len);
break;
}
}
/* 32-bit alignment */
avio_skip(pb, ((avio_tell(pb) + 3) & ~3) - avio_tell(pb));
} else
avio_seek(pb, 4, SEEK_SET);
if (has_packet_info) {
avpriv_request_sample(s, "RTP-X-QT with packet-specific info");
return AVERROR_PATCHWELCOME;
}
alen = len - avio_tell(pb);
if (alen <= 0)
return AVERROR_INVALIDDATA;
switch (packing_scheme) {
case 3: /* one data packet spread over 1 or multiple RTP packets */
if (qt->pkt->size > 0 && qt->timestamp == *timestamp) {
int err;
if ((err = av_reallocp(&qt->pkt->data, qt->pkt->size + alen +
AV_INPUT_BUFFER_PADDING_SIZE)) < 0) {
qt->pkt->size = 0;
return err;
}
} else {
av_freep(&qt->pkt->data);
av_packet_unref(qt->pkt);
qt->pkt->data = av_realloc(NULL, alen + AV_INPUT_BUFFER_PADDING_SIZE);
if (!qt->pkt->data)
return AVERROR(ENOMEM);
qt->pkt->size = 0;
qt->timestamp = *timestamp;
}
memcpy(qt->pkt->data + qt->pkt->size, buf + avio_tell(pb), alen);
qt->pkt->size += alen;
if (has_marker_bit) {
int ret = av_packet_from_data(pkt, qt->pkt->data, qt->pkt->size);
if (ret < 0)
return ret;
qt->pkt->size = 0;
qt->pkt->data = NULL;
pkt->flags = keyframe ? AV_PKT_FLAG_KEY : 0;
pkt->stream_index = st->index;
memset(pkt->data + pkt->size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
return 0;
}
return AVERROR(EAGAIN);
case 1: /* constant packet size, multiple packets per RTP packet */
if (qt->bytes_per_frame == 0 ||
alen % qt->bytes_per_frame != 0)
return AVERROR_INVALIDDATA; /* wrongly padded */
qt->remaining = (alen / qt->bytes_per_frame) - 1;
if ((ret = av_new_packet(pkt, qt->bytes_per_frame)) < 0)
return ret;
memcpy(pkt->data, buf + avio_tell(pb), qt->bytes_per_frame);
pkt->flags = keyframe ? AV_PKT_FLAG_KEY : 0;
pkt->stream_index = st->index;
if (qt->remaining > 0) {
av_freep(&qt->pkt->data);
qt->pkt->data = av_realloc(NULL, qt->remaining * qt->bytes_per_frame);
if (!qt->pkt->data) {
av_packet_unref(pkt);
return AVERROR(ENOMEM);
}
qt->pkt->size = qt->remaining * qt->bytes_per_frame;
memcpy(qt->pkt->data,
buf + avio_tell(pb) + qt->bytes_per_frame,
qt->remaining * qt->bytes_per_frame);
qt->pkt->flags = pkt->flags;
return 1;
}
return 0;
default: /* unimplemented */
avpriv_request_sample(NULL, "RTP-X-QT with packing scheme 2");
return AVERROR_PATCHWELCOME;
}
}
static void qt_rtp_close(PayloadContext *qt)
{
av_freep(&qt->pkt->data);
av_packet_free(&qt->pkt);
}
#define RTP_QT_HANDLER(m, n, s, t) \
const RTPDynamicProtocolHandler ff_ ## m ## _rtp_ ## n ## _handler = { \
.enc_name = s, \
.codec_type = t, \
.codec_id = AV_CODEC_ID_NONE, \
.priv_data_size = sizeof(PayloadContext), \
.init = qt_rtp_init, \
.close = qt_rtp_close, \
.parse_packet = qt_rtp_parse_packet, \
}
RTP_QT_HANDLER(qt, vid, "X-QT", AVMEDIA_TYPE_VIDEO);
RTP_QT_HANDLER(qt, aud, "X-QT", AVMEDIA_TYPE_AUDIO);
RTP_QT_HANDLER(quicktime, vid, "X-QUICKTIME", AVMEDIA_TYPE_VIDEO);
RTP_QT_HANDLER(quicktime, aud, "X-QUICKTIME", AVMEDIA_TYPE_AUDIO);
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