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wavpack: fix clipping for 32-bit lossy mode 

Reference decoder clips data before shifting it to final range and also
forces 32-bit lossy mode to be actually 24-bit lossy mode in order to be
able to perform proper clipping.
This commit is contained in:
Kostya Shishkov 2012-01-15 14:23:28 +01:00
parent 4fccc7c46c
commit e6e7bfc11e
1 changed files with 19 additions and 8 deletions
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27
libavcodec/wavpack.c
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@ -112,7 +112,8 @@ typedef struct WavpackFrameContext {
int extra_bits;
int and, or, shift;
int post_shift;
int hybrid, hybrid_bitrate, hybrid_maxclip;
int hybrid, hybrid_bitrate;
int hybrid_maxclip, hybrid_minclip;
int float_flag;
int float_shift;
int float_max_exp;
@ -412,12 +413,12 @@ static inline int wv_get_value_integer(WavpackFrameContext *s, uint32_t *crc,
}
bit = (S & s->and) | s->or;
bit = (((S + bit) << s->shift) - bit) << s->post_shift;
bit = ((S + bit) << s->shift) - bit;
if (s->hybrid)
bit = av_clip(bit, -s->hybrid_maxclip - 1, s->hybrid_maxclip);
bit = av_clip(bit, s->hybrid_minclip, s->hybrid_maxclip);
return bit;
return bit << s->post_shift;
}
static float wv_get_value_float(WavpackFrameContext *s, uint32_t *crc, int S)
@ -763,7 +764,7 @@ static int wavpack_decode_block(AVCodecContext *avctx, int block_no,
const uint8_t *orig_buf = buf;
const uint8_t *buf_end = buf + buf_size;
int i, j, id, size, ssize, weights, t;
int bpp, chan, chmask;
int bpp, chan, chmask, orig_bpp;
if (buf_size == 0) {
*got_frame_ptr = 0;
@ -799,15 +800,16 @@ static int wavpack_decode_block(AVCodecContext *avctx, int block_no,
s->frame_flags = AV_RL32(buf); buf += 4;
bpp = av_get_bytes_per_sample(avctx->sample_fmt);
samples = (uint8_t*)samples + bpp * wc->ch_offset;
orig_bpp = ((s->frame_flags & 0x03) + 1) << 3;
s->stereo = !(s->frame_flags & WV_MONO);
s->stereo_in = (s->frame_flags & WV_FALSE_STEREO) ? 0 : s->stereo;
s->joint = s->frame_flags & WV_JOINT_STEREO;
s->hybrid = s->frame_flags & WV_HYBRID_MODE;
s->hybrid_bitrate = s->frame_flags & WV_HYBRID_BITRATE;
s->hybrid_maxclip = (1LL << ((((s->frame_flags & 0x03) + 1) << 3) - 1)) - 1;
s->post_shift = 8 * (bpp - 1 - (s->frame_flags & 0x03)) +
((s->frame_flags >> 13) & 0x1f);
s->post_shift = bpp * 8 - orig_bpp + ((s->frame_flags >> 13) & 0x1f);
s->hybrid_maxclip = (( 1LL << (orig_bpp - 1)) - 1) >> s->post_shift;
s->hybrid_minclip = ((-1LL << (orig_bpp - 1))) >> s->post_shift;
s->CRC = AV_RL32(buf); buf += 4;
if (wc->mkv_mode)
buf += 4; //skip block size;
@ -968,6 +970,15 @@ static int wavpack_decode_block(AVCodecContext *avctx, int block_no,
s->and = 1;
s->shift = buf[3];
}
/* original WavPack decoder forces 32-bit lossy sound to be treated
* as 24-bit one in order to have proper clipping
*/
if (s->hybrid && bpp == 4 && s->post_shift < 8 && s->shift > 8) {
s->post_shift += 8;
s->shift -= 8;
s->hybrid_maxclip >>= 8;
s->hybrid_minclip >>= 8;
}
buf += 4;
break;
case WP_ID_FLOATINFO: