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flacdec: split frame header decoding and validation into a separate

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function

Originally committed as revision 18175 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2009-03-24 01:17:55 +00:00
parent 77544e5b91
commit cd98a03024
2 changed files with 68 additions and 40 deletions
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15
libavcodec/flac.h
View File

@ -57,22 +57,31 @@ enum FLACExtradataFormat {
FLAC_EXTRADATA_FORMAT_FULL_HEADER = 1 FLAC_EXTRADATA_FORMAT_FULL_HEADER = 1
}; };
#define FLACCOMMONINFO \
int samplerate; /**< sample rate */\
int channels; /**< number of channels */\
int bps; /**< bits-per-sample */\
/** /**
* Data needed from the Streaminfo header for use by the raw FLAC demuxer * Data needed from the Streaminfo header for use by the raw FLAC demuxer
* and/or the FLAC decoder. * and/or the FLAC decoder.
*/ */
#define FLACSTREAMINFO \ #define FLACSTREAMINFO \
FLACCOMMONINFO \
int max_blocksize; /**< maximum block size, in samples */\ int max_blocksize; /**< maximum block size, in samples */\
int max_framesize; /**< maximum frame size, in bytes */\ int max_framesize; /**< maximum frame size, in bytes */\
int samplerate; /**< sample rate */\
int channels; /**< number of channels */\
int bps; /**< bits-per-sample */\
int64_t samples; /**< total number of samples */\ int64_t samples; /**< total number of samples */\
typedef struct FLACStreaminfo { typedef struct FLACStreaminfo {
FLACSTREAMINFO FLACSTREAMINFO
} FLACStreaminfo; } FLACStreaminfo;
typedef struct FLACFrameInfo {
FLACCOMMONINFO
int blocksize; /**< block size of the frame */
int ch_mode; /**< channel decorrelation mode */
} FLACFrameInfo;
/** /**
* Parse the Streaminfo metadata block * Parse the Streaminfo metadata block
* @param[out] avctx codec context to set basic stream parameters * @param[out] avctx codec context to set basic stream parameters

93
libavcodec/flacdec.c
View File

@ -480,75 +480,80 @@ static inline int decode_subframe(FLACContext *s, int channel)
return 0; return 0;
} }
static int decode_frame(FLACContext *s) /**
* Validate and decode a frame header.
* @param avctx AVCodecContext to use as av_log() context
* @param gb GetBitContext from which to read frame header
* @param[out] fi frame information
*/
static int decode_frame_header(AVCodecContext *avctx, GetBitContext *gb,
FLACFrameInfo *fi)
{ {
int bs_code, sr_code, bps_code, i; int bs_code, sr_code, bps_code;
int ch_mode, bps, blocksize, samplerate, channels;
GetBitContext *gb = &s->gb;
/* frame sync code */ /* frame sync code */
skip_bits(&s->gb, 16); skip_bits(gb, 16);
/* block size and sample rate codes */ /* block size and sample rate codes */
bs_code = get_bits(gb, 4); bs_code = get_bits(gb, 4);
sr_code = get_bits(gb, 4); sr_code = get_bits(gb, 4);
/* channels and decorrelation */ /* channels and decorrelation */
ch_mode = get_bits(gb, 4); fi->ch_mode = get_bits(gb, 4);
if (ch_mode < FLAC_MAX_CHANNELS) { if (fi->ch_mode < FLAC_MAX_CHANNELS) {
channels = ch_mode + 1; fi->channels = fi->ch_mode + 1;
ch_mode = FLAC_CHMODE_INDEPENDENT; fi->ch_mode = FLAC_CHMODE_INDEPENDENT;
} else if (ch_mode <= FLAC_CHMODE_MID_SIDE) { } else if (fi->ch_mode <= FLAC_CHMODE_MID_SIDE) {
channels = 2; fi->channels = 2;
} else { } else {
av_log(s->avctx, AV_LOG_ERROR, "invalid channel mode: %d\n", ch_mode); av_log(avctx, AV_LOG_ERROR, "invalid channel mode: %d\n", fi->ch_mode);
return -1; return -1;
} }
/* bits per sample */ /* bits per sample */
bps_code = get_bits(gb, 3); bps_code = get_bits(gb, 3);
if (bps_code == 3 || bps_code == 7) { if (bps_code == 3 || bps_code == 7) {
av_log(s->avctx, AV_LOG_ERROR, "invalid sample size code (%d)\n", av_log(avctx, AV_LOG_ERROR, "invalid sample size code (%d)\n",
bps_code); bps_code);
return -1; return -1;
} }
bps = sample_size_table[bps_code]; fi->bps = sample_size_table[bps_code];
/* reserved bit */ /* reserved bit */
if (get_bits1(gb)) { if (get_bits1(gb)) {
av_log(s->avctx, AV_LOG_ERROR, "broken stream, invalid padding\n"); av_log(avctx, AV_LOG_ERROR, "broken stream, invalid padding\n");
return -1; return -1;
} }
/* sample or frame count */ /* sample or frame count */
if (get_utf8(gb) < 0) { if (get_utf8(gb) < 0) {
av_log(s->avctx, AV_LOG_ERROR, "utf8 fscked\n"); av_log(avctx, AV_LOG_ERROR, "utf8 fscked\n");
return -1; return -1;
} }
/* blocksize */ /* blocksize */
if (bs_code == 0) { if (bs_code == 0) {
av_log(s->avctx, AV_LOG_ERROR, "reserved blocksize code: 0\n"); av_log(avctx, AV_LOG_ERROR, "reserved blocksize code: 0\n");
return -1; return -1;
} else if (bs_code == 6) { } else if (bs_code == 6) {
blocksize = get_bits(gb, 8) + 1; fi->blocksize = get_bits(gb, 8) + 1;
} else if (bs_code == 7) { } else if (bs_code == 7) {
blocksize = get_bits(gb, 16) + 1; fi->blocksize = get_bits(gb, 16) + 1;
} else { } else {
blocksize = ff_flac_blocksize_table[bs_code]; fi->blocksize = ff_flac_blocksize_table[bs_code];
} }
/* sample rate */ /* sample rate */
if (sr_code < 12) { if (sr_code < 12) {
samplerate = ff_flac_sample_rate_table[sr_code]; fi->samplerate = ff_flac_sample_rate_table[sr_code];
} else if (sr_code == 12) { } else if (sr_code == 12) {
samplerate = get_bits(gb, 8) * 1000; fi->samplerate = get_bits(gb, 8) * 1000;
} else if (sr_code == 13) { } else if (sr_code == 13) {
samplerate = get_bits(gb, 16); fi->samplerate = get_bits(gb, 16);
} else if (sr_code == 14) { } else if (sr_code == 14) {
samplerate = get_bits(gb, 16) * 10; fi->samplerate = get_bits(gb, 16) * 10;
} else { } else {
av_log(s->avctx, AV_LOG_ERROR, "illegal sample rate code %d\n", av_log(avctx, AV_LOG_ERROR, "illegal sample rate code %d\n",
sr_code); sr_code);
return -1; return -1;
} }
@ -557,18 +562,32 @@ static int decode_frame(FLACContext *s)
skip_bits(gb, 8); skip_bits(gb, 8);
if (av_crc(av_crc_get_table(AV_CRC_8_ATM), 0, gb->buffer, if (av_crc(av_crc_get_table(AV_CRC_8_ATM), 0, gb->buffer,
get_bits_count(gb)/8)) { get_bits_count(gb)/8)) {
av_log(s->avctx, AV_LOG_ERROR, "header crc mismatch\n"); av_log(avctx, AV_LOG_ERROR, "header crc mismatch\n");
return -1; return -1;
} }
if (channels != s->channels) { return 0;
}
static int decode_frame(FLACContext *s)
{
int i;
GetBitContext *gb = &s->gb;
FLACFrameInfo fi;
if (decode_frame_header(s->avctx, gb, &fi)) {
av_log(s->avctx, AV_LOG_ERROR, "invalid frame header\n");
return -1;
}
if (fi.channels != s->channels) {
av_log(s->avctx, AV_LOG_ERROR, "switching channel layout mid-stream " av_log(s->avctx, AV_LOG_ERROR, "switching channel layout mid-stream "
"is not supported\n"); "is not supported\n");
return -1; return -1;
} }
s->ch_mode = ch_mode; s->ch_mode = fi.ch_mode;
if (bps && bps != s->bps) { if (fi.bps && fi.bps != s->bps) {
av_log(s->avctx, AV_LOG_ERROR, "switching bps mid-stream is not " av_log(s->avctx, AV_LOG_ERROR, "switching bps mid-stream is not "
"supported\n"); "supported\n");
return -1; return -1;
@ -583,20 +602,20 @@ static int decode_frame(FLACContext *s)
s->is32 = 0; s->is32 = 0;
} }
if (blocksize > s->max_blocksize) { if (fi.blocksize > s->max_blocksize) {
av_log(s->avctx, AV_LOG_ERROR, "blocksize %d > %d\n", blocksize, av_log(s->avctx, AV_LOG_ERROR, "blocksize %d > %d\n", fi.blocksize,
s->max_blocksize); s->max_blocksize);
return -1; return -1;
} }
s->blocksize = blocksize; s->blocksize = fi.blocksize;
if (samplerate == 0) { if (fi.samplerate == 0) {
samplerate = s->samplerate; fi.samplerate = s->samplerate;
} else if (samplerate != s->samplerate) { } else if (fi.samplerate != s->samplerate) {
av_log(s->avctx, AV_LOG_WARNING, "sample rate changed from %d to %d\n", av_log(s->avctx, AV_LOG_WARNING, "sample rate changed from %d to %d\n",
s->samplerate, samplerate); s->samplerate, fi.samplerate);
} }
s->samplerate = s->avctx->sample_rate = samplerate; s->samplerate = s->avctx->sample_rate = fi.samplerate;
// dump_headers(s->avctx, (FLACStreaminfo *)s); // dump_headers(s->avctx, (FLACStreaminfo *)s);