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FFmpeg/libavformat/pva.c

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/*
* TechnoTrend PVA (.pva) demuxer
* Copyright (c) 2007, 2008 Ivo van Poorten
*
* 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
*/
#include "avformat.h"
#include "internal.h"
#include "mpeg.h"
#define PVA_MAX_PAYLOAD_LENGTH 0x17f8
#define PVA_VIDEO_PAYLOAD 0x01
#define PVA_AUDIO_PAYLOAD 0x02
#define PVA_MAGIC (('A' << 8) + 'V')
typedef struct PVAContext {
int continue_pes;
} PVAContext;
static int pva_check(const uint8_t *p) {
int length = AV_RB16(p + 6);
if (AV_RB16(p) != PVA_MAGIC || !p[2] || p[2] > 2 || p[4] != 0x55 ||
(p[5] & 0xe0) || length > PVA_MAX_PAYLOAD_LENGTH)
return -1;
return length + 8;
}
static int pva_probe(const AVProbeData * pd) {
const unsigned char *buf = pd->buf;
int len = pva_check(buf);
if (len < 0)
return 0;
if (pd->buf_size >= len + 8 &&
pva_check(buf + len) >= 0)
return AVPROBE_SCORE_EXTENSION;
return AVPROBE_SCORE_MAX / 4;
}
static int pva_read_header(AVFormatContext *s) {
AVStream *st;
if (!(st = avformat_new_stream(s, NULL)))
return AVERROR(ENOMEM);
lavf: replace AVStream.codec with AVStream.codecpar Currently, AVStream contains an embedded AVCodecContext instance, which is used by demuxers to export stream parameters to the caller and by muxers to receive stream parameters from the caller. It is also used internally as the codec context that is passed to parsers. In addition, it is also widely used by the callers as the decoding (when demuxer) or encoding (when muxing) context, though this has been officially discouraged since Libav 11. There are multiple important problems with this approach: - the fields in AVCodecContext are in general one of * stream parameters * codec options * codec state However, it's not clear which ones are which. It is consequently unclear which fields are a demuxer allowed to set or a muxer allowed to read. This leads to erratic behaviour depending on whether decoding or encoding is being performed or not (and whether it uses the AVStream embedded codec context). - various synchronization issues arising from the fact that the same context is used by several different APIs (muxers/demuxers, parsers, bitstream filters and encoders/decoders) simultaneously, with there being no clear rules for who can modify what and the different processes being typically delayed with respect to each other. - avformat_find_stream_info() making it necessary to support opening and closing a single codec context multiple times, thus complicating the semantics of freeing various allocated objects in the codec context. Those problems are resolved by replacing the AVStream embedded codec context with a newly added AVCodecParameters instance, which stores only the stream parameters exported by the demuxers or read by the muxers.
2014-06-18 21:42:52 +03:00
st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
st->codecpar->codec_id = AV_CODEC_ID_MPEG2VIDEO;
st->need_parsing = AVSTREAM_PARSE_FULL;
avpriv_set_pts_info(st, 32, 1, 90000);
av_add_index_entry(st, 0, 0, 0, 0, AVINDEX_KEYFRAME);
if (!(st = avformat_new_stream(s, NULL)))
return AVERROR(ENOMEM);
lavf: replace AVStream.codec with AVStream.codecpar Currently, AVStream contains an embedded AVCodecContext instance, which is used by demuxers to export stream parameters to the caller and by muxers to receive stream parameters from the caller. It is also used internally as the codec context that is passed to parsers. In addition, it is also widely used by the callers as the decoding (when demuxer) or encoding (when muxing) context, though this has been officially discouraged since Libav 11. There are multiple important problems with this approach: - the fields in AVCodecContext are in general one of * stream parameters * codec options * codec state However, it's not clear which ones are which. It is consequently unclear which fields are a demuxer allowed to set or a muxer allowed to read. This leads to erratic behaviour depending on whether decoding or encoding is being performed or not (and whether it uses the AVStream embedded codec context). - various synchronization issues arising from the fact that the same context is used by several different APIs (muxers/demuxers, parsers, bitstream filters and encoders/decoders) simultaneously, with there being no clear rules for who can modify what and the different processes being typically delayed with respect to each other. - avformat_find_stream_info() making it necessary to support opening and closing a single codec context multiple times, thus complicating the semantics of freeing various allocated objects in the codec context. Those problems are resolved by replacing the AVStream embedded codec context with a newly added AVCodecParameters instance, which stores only the stream parameters exported by the demuxers or read by the muxers.
2014-06-18 21:42:52 +03:00
st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
st->codecpar->codec_id = AV_CODEC_ID_MP2;
st->need_parsing = AVSTREAM_PARSE_FULL;
avpriv_set_pts_info(st, 33, 1, 90000);
av_add_index_entry(st, 0, 0, 0, 0, AVINDEX_KEYFRAME);
/* the parameters will be extracted from the compressed bitstream */
return 0;
}
#define pva_log if (read_packet) av_log
static int read_part_of_packet(AVFormatContext *s, int64_t *pts,
int *len, int *strid, int read_packet) {
AVIOContext *pb = s->pb;
PVAContext *pvactx = s->priv_data;
int syncword, streamid, reserved, flags, length, pts_flag;
int64_t pva_pts = AV_NOPTS_VALUE, startpos;
int ret;
recover:
startpos = avio_tell(pb);
syncword = avio_rb16(pb);
streamid = avio_r8(pb);
avio_r8(pb); /* counter not used */
reserved = avio_r8(pb);
flags = avio_r8(pb);
length = avio_rb16(pb);
pts_flag = flags & 0x10;
if (syncword != PVA_MAGIC) {
pva_log(s, AV_LOG_ERROR, "invalid syncword\n");
return AVERROR(EIO);
}
if (streamid != PVA_VIDEO_PAYLOAD && streamid != PVA_AUDIO_PAYLOAD) {
pva_log(s, AV_LOG_ERROR, "invalid streamid\n");
return AVERROR(EIO);
}
if (reserved != 0x55) {
pva_log(s, AV_LOG_WARNING, "expected reserved byte to be 0x55\n");
}
if (length > PVA_MAX_PAYLOAD_LENGTH) {
pva_log(s, AV_LOG_ERROR, "invalid payload length %u\n", length);
return AVERROR(EIO);
}
if (streamid == PVA_VIDEO_PAYLOAD && pts_flag) {
pva_pts = avio_rb32(pb);
length -= 4;
} else if (streamid == PVA_AUDIO_PAYLOAD) {
/* PVA Audio Packets either start with a signaled PES packet or
* are a continuation of the previous PES packet. New PES packets
* always start at the beginning of a PVA Packet, never somewhere in
* the middle. */
if (!pvactx->continue_pes) {
int pes_signal, pes_header_data_length, pes_packet_length,
pes_flags;
unsigned char pes_header_data[256];
pes_signal = avio_rb24(pb);
avio_r8(pb);
pes_packet_length = avio_rb16(pb);
pes_flags = avio_rb16(pb);
pes_header_data_length = avio_r8(pb);
if (avio_feof(pb)) {
return AVERROR_EOF;
}
if (pes_signal != 1 || pes_header_data_length == 0) {
pva_log(s, AV_LOG_WARNING, "expected non empty signaled PES packet, "
"trying to recover\n");
avio_skip(pb, length - 9);
if (!read_packet)
return AVERROR(EIO);
goto recover;
}
ret = avio_read(pb, pes_header_data, pes_header_data_length);
if (ret != pes_header_data_length)
return ret < 0 ? ret : AVERROR_INVALIDDATA;
length -= 9 + pes_header_data_length;
pes_packet_length -= 3 + pes_header_data_length;
pvactx->continue_pes = pes_packet_length;
if (pes_flags & 0x80 && (pes_header_data[0] & 0xf0) == 0x20) {
if (pes_header_data_length < 5) {
pva_log(s, AV_LOG_ERROR, "header too short\n");
avio_skip(pb, length);
return AVERROR_INVALIDDATA;
}
pva_pts = ff_parse_pes_pts(pes_header_data);
}
}
pvactx->continue_pes -= length;
if (pvactx->continue_pes < 0) {
pva_log(s, AV_LOG_WARNING, "audio data corruption\n");
pvactx->continue_pes = 0;
}
}
if (pva_pts != AV_NOPTS_VALUE)
av_add_index_entry(s->streams[streamid-1], startpos, pva_pts, 0, 0, AVINDEX_KEYFRAME);
*pts = pva_pts;
*len = length;
*strid = streamid;
return 0;
}
static int pva_read_packet(AVFormatContext *s, AVPacket *pkt) {
AVIOContext *pb = s->pb;
int64_t pva_pts;
int ret, length, streamid;
if (read_part_of_packet(s, &pva_pts, &length, &streamid, 1) < 0 ||
(ret = av_get_packet(pb, pkt, length)) <= 0)
return AVERROR(EIO);
pkt->stream_index = streamid - 1;
pkt->pts = pva_pts;
return ret;
}
static int64_t pva_read_timestamp(struct AVFormatContext *s, int stream_index,
int64_t *pos, int64_t pos_limit) {
AVIOContext *pb = s->pb;
PVAContext *pvactx = s->priv_data;
int length, streamid;
int64_t res = AV_NOPTS_VALUE;
pos_limit = FFMIN(*pos+PVA_MAX_PAYLOAD_LENGTH*8, (uint64_t)*pos+pos_limit);
while (*pos < pos_limit) {
res = AV_NOPTS_VALUE;
avio_seek(pb, *pos, SEEK_SET);
pvactx->continue_pes = 0;
if (read_part_of_packet(s, &res, &length, &streamid, 0)) {
(*pos)++;
continue;
}
if (streamid - 1 != stream_index || res == AV_NOPTS_VALUE) {
*pos = avio_tell(pb) + length;
continue;
}
break;
}
pvactx->continue_pes = 0;
return res;
}
AVInputFormat ff_pva_demuxer = {
.name = "pva",
.long_name = NULL_IF_CONFIG_SMALL("TechnoTrend PVA"),
.priv_data_size = sizeof(PVAContext),
.read_probe = pva_probe,
.read_header = pva_read_header,
.read_packet = pva_read_packet,
.read_timestamp = pva_read_timestamp,
};