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DEFINITIONS
This source file includes following definitions.
- mpc_probe
- mpc_read_header
- mpc_read_packet
- mpc_read_close
- mpc_read_seek
/*
* Musepack demuxer
* Copyright (c) 2006 Konstantin Shishkov
*
* 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 "libavcodec/bitstream.h"
#include "avformat.h"
#include "id3v2.h"
#define MPC_FRAMESIZE 1152
#define DELAY_FRAMES 32
static const int mpc_rate[4] = { 44100, 48000, 37800, 32000 };
typedef struct {
int64_t pos;
int size, skip;
}MPCFrame;
typedef struct {
int ver;
uint32_t curframe, lastframe;
uint32_t fcount;
MPCFrame *frames;
int curbits;
int frames_noted;
} MPCContext;
static int mpc_probe(AVProbeData *p)
{
const uint8_t *d = p->buf;
if (ff_id3v2_match(d)) {
d += ff_id3v2_tag_len(d);
}
if (d+3 < p->buf+p->buf_size)
if (d[0] == 'M' && d[1] == 'P' && d[2] == '+' && (d[3] == 0x17 || d[3] == 0x7))
return AVPROBE_SCORE_MAX;
return 0;
}
static int mpc_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
MPCContext *c = s->priv_data;
AVStream *st;
int t;
t = get_le24(s->pb);
if(t != MKTAG('M', 'P', '+', 0)){
if(t != MKTAG('I', 'D', '3', 0)){
av_log(s, AV_LOG_ERROR, "Not a Musepack file\n");
return -1;
}
/* skip ID3 tags and try again */
url_fskip(s->pb, 3);
t = get_byte(s->pb) << 21;
t |= get_byte(s->pb) << 14;
t |= get_byte(s->pb) << 7;
t |= get_byte(s->pb);
av_log(s, AV_LOG_DEBUG, "Skipping %d(%X) bytes of ID3 data\n", t, t);
url_fskip(s->pb, t);
if(get_le24(s->pb) != MKTAG('M', 'P', '+', 0)){
av_log(s, AV_LOG_ERROR, "Not a Musepack file\n");
return -1;
}
}
c->ver = get_byte(s->pb);
if(c->ver != 0x07 && c->ver != 0x17){
av_log(s, AV_LOG_ERROR, "Can demux Musepack SV7, got version %02X\n", c->ver);
return -1;
}
c->fcount = get_le32(s->pb);
if((int64_t)c->fcount * sizeof(MPCFrame) >= UINT_MAX){
av_log(s, AV_LOG_ERROR, "Too many frames, seeking is not possible\n");
return -1;
}
c->frames = av_malloc(c->fcount * sizeof(MPCFrame));
c->curframe = 0;
c->lastframe = -1;
c->curbits = 8;
c->frames_noted = 0;
st = av_new_stream(s, 0);
if (!st)
return AVERROR(ENOMEM);
st->codec->codec_type = CODEC_TYPE_AUDIO;
st->codec->codec_id = CODEC_ID_MUSEPACK7;
st->codec->channels = 2;
st->codec->bits_per_coded_sample = 16;
st->codec->extradata_size = 16;
st->codec->extradata = av_mallocz(st->codec->extradata_size+FF_INPUT_BUFFER_PADDING_SIZE);
get_buffer(s->pb, st->codec->extradata, 16);
st->codec->sample_rate = mpc_rate[st->codec->extradata[2] & 3];
av_set_pts_info(st, 32, MPC_FRAMESIZE, st->codec->sample_rate);
/* scan for seekpoints */
s->start_time = 0;
s->duration = (int64_t)c->fcount * MPC_FRAMESIZE * AV_TIME_BASE / st->codec->sample_rate;
return 0;
}
static int mpc_read_packet(AVFormatContext *s, AVPacket *pkt)
{
MPCContext *c = s->priv_data;
int ret, size, size2, curbits, cur = c->curframe;
int64_t tmp, pos;
if (c->curframe >= c->fcount)
return -1;
if(c->curframe != c->lastframe + 1){
url_fseek(s->pb, c->frames[c->curframe].pos, SEEK_SET);
c->curbits = c->frames[c->curframe].skip;
}
c->lastframe = c->curframe;
c->curframe++;
curbits = c->curbits;
pos = url_ftell(s->pb);
tmp = get_le32(s->pb);
if(curbits <= 12){
size2 = (tmp >> (12 - curbits)) & 0xFFFFF;
}else{
tmp = (tmp << 32) | get_le32(s->pb);
size2 = (tmp >> (44 - curbits)) & 0xFFFFF;
}
curbits += 20;
url_fseek(s->pb, pos, SEEK_SET);
size = ((size2 + curbits + 31) & ~31) >> 3;
if(cur == c->frames_noted){
c->frames[cur].pos = pos;
c->frames[cur].size = size;
c->frames[cur].skip = curbits - 20;
av_add_index_entry(s->streams[0], cur, cur, size, 0, AVINDEX_KEYFRAME);
c->frames_noted++;
}
c->curbits = (curbits + size2) & 0x1F;
if (av_new_packet(pkt, size) < 0)
return AVERROR(EIO);
pkt->data[0] = curbits;
pkt->data[1] = (c->curframe > c->fcount);
pkt->stream_index = 0;
pkt->pts = cur;
ret = get_buffer(s->pb, pkt->data + 4, size);
if(c->curbits)
url_fseek(s->pb, -4, SEEK_CUR);
if(ret < size){
av_free_packet(pkt);
return AVERROR(EIO);
}
pkt->size = ret + 4;
return 0;
}
static int mpc_read_close(AVFormatContext *s)
{
MPCContext *c = s->priv_data;
av_freep(&c->frames);
return 0;
}
/**
* Seek to the given position
* If position is unknown but is within the limits of file
* then packets are skipped unless desired position is reached
*
* Also this function makes use of the fact that timestamp == frameno
*/
static int mpc_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
{
AVStream *st = s->streams[stream_index];
MPCContext *c = s->priv_data;
AVPacket pkt1, *pkt = &pkt1;
int ret;
int index = av_index_search_timestamp(st, timestamp - DELAY_FRAMES, flags);
uint32_t lastframe;
/* if found, seek there */
if (index >= 0){
c->curframe = st->index_entries[index].pos;
return 0;
}
/* if timestamp is out of bounds, return error */
if(timestamp < 0 || timestamp >= c->fcount)
return -1;
timestamp -= DELAY_FRAMES;
/* seek to the furthest known position and read packets until
we reach desired position */
lastframe = c->curframe;
if(c->frames_noted) c->curframe = c->frames_noted - 1;
while(c->curframe < timestamp){
ret = av_read_frame(s, pkt);
if (ret < 0){
c->curframe = lastframe;
return -1;
}
av_free_packet(pkt);
}
return 0;
}
AVInputFormat mpc_demuxer = {
"mpc",
NULL_IF_CONFIG_SMALL("Musepack"),
sizeof(MPCContext),
mpc_probe,
mpc_read_header,
mpc_read_packet,
mpc_read_close,
mpc_read_seek,
.extensions = "mpc",
};