FFmpeg/libavformat/mpc8.c
Anton Khirnov 9200514ad8 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.
2016-02-23 17:01:58 +01:00

316 lines
8.6 KiB
C

/*
* Musepack SV8 demuxer
* Copyright (c) 2007 Konstantin Shishkov
*
* 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 "libavcodec/get_bits.h"
#include "libavcodec/unary.h"
#include "apetag.h"
#include "avformat.h"
#include "internal.h"
#include "avio_internal.h"
/// Two-byte MPC tag
#define MKMPCTAG(a, b) (a | (b << 8))
#define TAG_MPCK MKTAG('M','P','C','K')
/// Reserved MPC tags
enum MPCPacketTags{
TAG_STREAMHDR = MKMPCTAG('S','H'),
TAG_STREAMEND = MKMPCTAG('S','E'),
TAG_AUDIOPACKET = MKMPCTAG('A','P'),
TAG_SEEKTBLOFF = MKMPCTAG('S','O'),
TAG_SEEKTABLE = MKMPCTAG('S','T'),
TAG_REPLAYGAIN = MKMPCTAG('R','G'),
TAG_ENCINFO = MKMPCTAG('E','I'),
};
static const int mpc8_rate[8] = { 44100, 48000, 37800, 32000, -1, -1, -1, -1 };
typedef struct MPCContext {
int ver;
int64_t header_pos;
int64_t samples;
int64_t apetag_start;
} MPCContext;
static inline int64_t bs_get_v(uint8_t **bs)
{
int64_t v = 0;
int br = 0;
int c;
do {
c = **bs; (*bs)++;
v <<= 7;
v |= c & 0x7F;
br++;
if (br > 10)
return -1;
} while (c & 0x80);
return v - br;
}
static int mpc8_probe(AVProbeData *p)
{
uint8_t *bs = p->buf + 4;
uint8_t *bs_end = bs + p->buf_size;
int64_t size;
if (p->buf_size < 16)
return 0;
if (AV_RL32(p->buf) != TAG_MPCK)
return 0;
while (bs < bs_end + 3) {
int header_found = (bs[0] == 'S' && bs[1] == 'H');
if (bs[0] < 'A' || bs[0] > 'Z' || bs[1] < 'A' || bs[1] > 'Z')
return 0;
bs += 2;
size = bs_get_v(&bs);
if (size < 2)
return 0;
if (bs + size - 2 >= bs_end)
return AVPROBE_SCORE_EXTENSION - 1; // seems to be valid MPC but no header yet
if (header_found) {
if (size < 11 || size > 28)
return 0;
if (!AV_RL32(bs)) //zero CRC is invalid
return 0;
return AVPROBE_SCORE_MAX;
} else {
bs += size - 2;
}
}
return 0;
}
static inline int64_t gb_get_v(GetBitContext *gb)
{
int64_t v = 0;
int bits = 0;
while(get_bits1(gb) && bits < 64-7){
v <<= 7;
v |= get_bits(gb, 7);
bits += 7;
}
v <<= 7;
v |= get_bits(gb, 7);
return v;
}
static void mpc8_get_chunk_header(AVIOContext *pb, int *tag, int64_t *size)
{
int64_t pos;
pos = avio_tell(pb);
*tag = avio_rl16(pb);
*size = ffio_read_varlen(pb);
*size -= avio_tell(pb) - pos;
}
static void mpc8_parse_seektable(AVFormatContext *s, int64_t off)
{
MPCContext *c = s->priv_data;
int tag;
int64_t size, pos, ppos[2];
uint8_t *buf;
int i, t, seekd;
GetBitContext gb;
if (s->nb_streams == 0) {
av_log(s, AV_LOG_ERROR, "No stream added before parsing seek table\n");
return;
}
avio_seek(s->pb, off, SEEK_SET);
mpc8_get_chunk_header(s->pb, &tag, &size);
if(tag != TAG_SEEKTABLE){
av_log(s, AV_LOG_ERROR, "No seek table at given position\n");
return;
}
if (size < 0 || size >= INT_MAX / 2) {
av_log(s, AV_LOG_ERROR, "Bad seek table size\n");
return;
}
if(!(buf = av_malloc(size + AV_INPUT_BUFFER_PADDING_SIZE)))
return;
avio_read(s->pb, buf, size);
init_get_bits(&gb, buf, size * 8);
size = gb_get_v(&gb);
if(size > UINT_MAX/4 || size > c->samples/1152){
av_log(s, AV_LOG_ERROR, "Seek table is too big\n");
return;
}
seekd = get_bits(&gb, 4);
for(i = 0; i < 2; i++){
pos = gb_get_v(&gb) + c->header_pos;
ppos[1 - i] = pos;
av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME);
}
for(; i < size; i++){
t = get_unary(&gb, 1, 33) << 12;
t += get_bits(&gb, 12);
if(t & 1)
t = -(t & ~1);
pos = (t >> 1) + ppos[0]*2 - ppos[1];
av_add_index_entry(s->streams[0], pos, i << seekd, 0, 0, AVINDEX_KEYFRAME);
ppos[1] = ppos[0];
ppos[0] = pos;
}
av_free(buf);
}
static void mpc8_handle_chunk(AVFormatContext *s, int tag, int64_t chunk_pos, int64_t size)
{
AVIOContext *pb = s->pb;
int64_t pos, off;
switch(tag){
case TAG_SEEKTBLOFF:
pos = avio_tell(pb) + size;
off = ffio_read_varlen(pb);
mpc8_parse_seektable(s, chunk_pos + off);
avio_seek(pb, pos, SEEK_SET);
break;
default:
avio_skip(pb, size);
}
}
static int mpc8_read_header(AVFormatContext *s)
{
MPCContext *c = s->priv_data;
AVIOContext *pb = s->pb;
AVStream *st;
int tag = 0;
int64_t size, pos;
c->header_pos = avio_tell(pb);
if(avio_rl32(pb) != TAG_MPCK){
av_log(s, AV_LOG_ERROR, "Not a Musepack8 file\n");
return AVERROR_INVALIDDATA;
}
while(!pb->eof_reached){
pos = avio_tell(pb);
mpc8_get_chunk_header(pb, &tag, &size);
if(tag == TAG_STREAMHDR)
break;
mpc8_handle_chunk(s, tag, pos, size);
}
if(tag != TAG_STREAMHDR){
av_log(s, AV_LOG_ERROR, "Stream header not found\n");
return AVERROR_INVALIDDATA;
}
pos = avio_tell(pb);
avio_skip(pb, 4); //CRC
c->ver = avio_r8(pb);
if(c->ver != 8){
av_log(s, AV_LOG_ERROR, "Unknown stream version %d\n", c->ver);
return AVERROR_PATCHWELCOME;
}
c->samples = ffio_read_varlen(pb);
ffio_read_varlen(pb); //silence samples at the beginning
st = avformat_new_stream(s, NULL);
if (!st)
return AVERROR(ENOMEM);
st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
st->codecpar->codec_id = AV_CODEC_ID_MUSEPACK8;
st->codecpar->bits_per_coded_sample = 16;
st->codecpar->extradata_size = 2;
st->codecpar->extradata = av_mallocz(st->codecpar->extradata_size + AV_INPUT_BUFFER_PADDING_SIZE);
avio_read(pb, st->codecpar->extradata, st->codecpar->extradata_size);
st->codecpar->channels = (st->codecpar->extradata[1] >> 4) + 1;
st->codecpar->sample_rate = mpc8_rate[st->codecpar->extradata[0] >> 5];
avpriv_set_pts_info(st, 32, 1152 << (st->codecpar->extradata[1]&3)*2, st->codecpar->sample_rate);
st->start_time = 0;
st->duration = c->samples / (1152 << (st->codecpar->extradata[1]&3)*2);
size -= avio_tell(pb) - pos;
if (pb->seekable) {
int64_t pos = avio_tell(s->pb);
c->apetag_start = ff_ape_parse_tag(s);
avio_seek(s->pb, pos, SEEK_SET);
}
return 0;
}
static int mpc8_read_packet(AVFormatContext *s, AVPacket *pkt)
{
MPCContext *c = s->priv_data;
int tag;
int64_t pos, size;
while(!s->pb->eof_reached){
pos = avio_tell(s->pb);
/* don't return bogus packets with the ape tag data */
if (c->apetag_start && pos >= c->apetag_start)
return AVERROR_EOF;
mpc8_get_chunk_header(s->pb, &tag, &size);
if (size < 0)
return -1;
if(tag == TAG_AUDIOPACKET){
if(av_get_packet(s->pb, pkt, size) < 0)
return AVERROR(ENOMEM);
pkt->stream_index = 0;
pkt->duration = 1;
return 0;
}
if(tag == TAG_STREAMEND)
return AVERROR(EIO);
mpc8_handle_chunk(s, tag, pos, size);
}
return AVERROR_EOF;
}
static int mpc8_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
{
AVStream *st = s->streams[stream_index];
int index = av_index_search_timestamp(st, timestamp, flags);
if(index < 0) return -1;
if (avio_seek(s->pb, st->index_entries[index].pos, SEEK_SET) < 0)
return -1;
ff_update_cur_dts(s, st, st->index_entries[index].timestamp);
return 0;
}
AVInputFormat ff_mpc8_demuxer = {
.name = "mpc8",
.long_name = NULL_IF_CONFIG_SMALL("Musepack SV8"),
.priv_data_size = sizeof(MPCContext),
.read_probe = mpc8_probe,
.read_header = mpc8_read_header,
.read_packet = mpc8_read_packet,
.read_seek = mpc8_read_seek,
};