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adx: move header decoding to ADX common code

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This commit is contained in:
Justin Ruggles 2011-11-20 20:16:05 -05:00
parent 7ff55d9bdb
commit d8cec2d7fc
3 changed files with 74 additions and 36 deletions
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47
libavcodec/adx.c
View File

@ -18,6 +18,7 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/intreadwrite.h"
#include "libavutil/mathematics.h"
#include "adx.h"
@ -32,3 +33,49 @@ void ff_adx_calculate_coeffs(int cutoff, int sample_rate, int bits, int *coeff)
coeff[0] = lrintf(c * 2.0 * (1 << bits));
coeff[1] = lrintf(-(c * c) * (1 << bits));
}
int ff_adx_decode_header(AVCodecContext *avctx, const uint8_t *buf, int bufsize,
int *header_size, int *coeff)
{
int offset, cutoff;
if (bufsize < 24)
return AVERROR_INVALIDDATA;
if (AV_RB16(buf) != 0x8000)
return AVERROR_INVALIDDATA;
offset = AV_RB16(buf + 2) + 4;
/* if copyright string is within the provided data, validate it */
if (bufsize >= offset && memcmp(buf + offset - 6, "(c)CRI", 6))
return AVERROR_INVALIDDATA;
/* check for encoding=3 block_size=18, sample_size=4 */
if (buf[4] != 3 || buf[5] != 18 || buf[6] != 4) {
av_log_ask_for_sample(avctx, "unsupported ADX format\n");
return AVERROR_PATCHWELCOME;
}
/* channels */
avctx->channels = buf[7];
if (avctx->channels > 2)
return AVERROR_INVALIDDATA;
/* sample rate */
avctx->sample_rate = AV_RB32(buf + 8);
if (avctx->sample_rate < 1 ||
avctx->sample_rate > INT_MAX / (avctx->channels * BLOCK_SIZE * 8))
return AVERROR_INVALIDDATA;
/* bit rate */
avctx->bit_rate = avctx->sample_rate * avctx->channels * BLOCK_SIZE * 8 / BLOCK_SAMPLES;
/* LPC coefficients */
if (coeff) {
cutoff = AV_RB16(buf + 16);
ff_adx_calculate_coeffs(cutoff, avctx->sample_rate, COEFF_BITS, coeff);
}
*header_size = offset;
return 0;
}

21
libavcodec/adx.h
View File

@ -31,6 +31,10 @@
#ifndef AVCODEC_ADX_H
#define AVCODEC_ADX_H
#include <stdint.h>
#include "avcodec.h"
typedef struct {
int s1,s2;
} ADXChannelState;
@ -47,6 +51,9 @@ typedef struct {
#define COEFF_BITS 12
#define BLOCK_SIZE 18
#define BLOCK_SAMPLES 32
/**
* Calculate LPC coefficients based on cutoff frequency and sample rate.
*
@ -57,4 +64,18 @@ typedef struct {
*/
void ff_adx_calculate_coeffs(int cutoff, int sample_rate, int bits, int *coeff);
/**
* Decode ADX stream header.
* Sets avctx->channels and avctx->sample_rate.
*
* @param avctx codec context
* @param buf header data
* @param bufsize data size, should be at least 24 bytes
* @param[out] header_size size of ADX header
* @param[out] coeff 2 LPC coefficients, can be NULL
* @return data offset or negative error code if header is invalid
*/
int ff_adx_decode_header(AVCodecContext *avctx, const uint8_t *buf, int bufsize,
int *header_size, int *coeff);
#endif /* AVCODEC_ADX_H */

42
libavcodec/adxdec.c
View File

@ -33,9 +33,6 @@
* adx2wav & wav2adx http://www.geocities.co.jp/Playtown/2004/
*/
#define BLOCK_SIZE 18
#define BLOCK_SAMPLES 32
static av_cold int adx_decode_init(AVCodecContext *avctx)
{
avctx->sample_fmt = AV_SAMPLE_FMT_S16;
@ -72,45 +69,18 @@ static void adx_decode(ADXContext *c, int16_t *out, const uint8_t *in, int ch)
prev->s2 = s2;
}
/**
* Decode stream header.
*
* @param avctx codec context
* @param buf packet data
* @param bufsize packet size
* @return data offset or negative error code if header is invalid
*/
static int adx_decode_header(AVCodecContext *avctx, const uint8_t *buf,
int bufsize)
{
ADXContext *c = avctx->priv_data;
int offset, cutoff;
int ret, header_size;
if (AV_RB16(buf) != 0x8000)
return AVERROR_INVALIDDATA;
offset = AV_RB16(buf + 2) + 4;
if (bufsize < offset || memcmp(buf + offset - 6, "(c)CRI", 6))
return AVERROR_INVALIDDATA;
if ((ret = ff_adx_decode_header(avctx, buf, bufsize, &header_size,
c->coeff)) < 0)
return ret;
/* check for encoding=3 block_size=18, sample_size=4 */
if (buf[4] != 3 || buf[5] != 18 || buf[6] != 4) {
av_log_ask_for_sample(avctx, "unsupported ADX format\n");
return AVERROR_PATCHWELCOME;
}
c->channels = avctx->channels = buf[7];
if (avctx->channels > 2)
return AVERROR_INVALIDDATA;
avctx->sample_rate = AV_RB32(buf + 8);
if (avctx->sample_rate < 1 ||
avctx->sample_rate > INT_MAX / (avctx->channels * BLOCK_SIZE * 8))
return AVERROR_INVALIDDATA;
avctx->bit_rate = avctx->sample_rate * avctx->channels * BLOCK_SIZE * 8 / BLOCK_SAMPLES;
cutoff = AV_RB16(buf + 16);
ff_adx_calculate_coeffs(cutoff, avctx->sample_rate, COEFF_BITS, c->coeff);
return offset;
c->channels = avctx->channels;
return header_size;
}
static int adx_decode_frame(AVCodecContext *avctx, void *data, int *data_size,