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Code Issues Releases Activity

Decode previous 32 frames to avoid seeking artifacts in MPC

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Originally committed as revision 7393 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Kostya Shishkov 2007-01-01 05:32:27 +00:00
parent 0587b0cacd
commit aac88b534c
2 changed files with 19 additions and 1 deletions
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15
libavcodec/mpc.c
View File

@ -51,6 +51,7 @@ typedef struct {
int lastframelen, bands;
int oldDSCF[2][BANDS];
int rnd;
int frames_to_skip;
/* for synthesis */
DECLARE_ALIGNED_16(MPA_INT, synth_buf[MPA_MAX_CHANNELS][512*2]);
int synth_buf_offset[MPA_MAX_CHANNELS];
@ -98,6 +99,7 @@ static int mpc7_decode_init(AVCodecContext * avctx)
c->lastframelen = get_bits(&gb, 11);
av_log(avctx, AV_LOG_DEBUG, "IS: %d, MSS: %d, TG: %d, LFL: %d, bands: %d\n",
c->IS, c->MSS, c->gapless, c->lastframelen, c->bands);
c->frames_to_skip = 0;
if(vlc_inited) return 0;
av_log(avctx, AV_LOG_DEBUG, "Initing VLC\n");
@ -328,11 +330,23 @@ static int mpc7_decode_frame(AVCodecContext * avctx,
av_log(NULL,0, "Error decoding frame: used %i of %i bits\n", bits_used, bits_avail);
return -1;
}
if(c->frames_to_skip){
c->frames_to_skip--;
*data_size = 0;
return buf_size;
}
*data_size = (buf[1] ? c->lastframelen : MPC_FRAME_SIZE) * 4;
return buf_size;
}
static void mpc7_decode_flush(AVCodecContext *avctx)
{
MPCContext *c = avctx->priv_data;
memset(c->oldDSCF, 0, sizeof(c->oldDSCF));
c->frames_to_skip = 32;
}
AVCodec mpc7_decoder = {
"mpc sv7",
@ -343,4 +357,5 @@ AVCodec mpc7_decoder = {
NULL,
NULL,
mpc7_decode_frame,
.flush = mpc7_decode_flush,
};

5
libavformat/mpc.c
View File

@ -22,6 +22,7 @@
#include "bitstream.h"
#define MPC_FRAMESIZE 1152
#define DELAY_FRAMES 32
static const int mpc_rate[4] = { 44100, 48000, 37800, 32000 };
typedef struct {
@ -155,6 +156,7 @@ static int mpc_read_packet(AVFormatContext *s, AVPacket *pkt)
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);
@ -188,7 +190,7 @@ static int mpc_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp
MPCContext *c = s->priv_data;
AVPacket pkt1, *pkt = &pkt1;
int ret;
int index = av_index_search_timestamp(st, timestamp, flags);
int index = av_index_search_timestamp(st, timestamp - DELAY_FRAMES, flags);
uint32_t lastframe;
/* if found, seek there */
@ -199,6 +201,7 @@ static int mpc_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp
/* 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;