[FFmpeg-cvslog] r21849 - trunk/libavcodec/alsdec.c
thilo.borgmann
subversion
Tue Feb 16 15:48:01 CET 2010
Author: thilo.borgmann
Date: Tue Feb 16 15:48:01 2010
New Revision: 21849
Log:
Limit the Rice parameter used for progressive decoding in ALS.
Modified:
trunk/libavcodec/alsdec.c
Modified: trunk/libavcodec/alsdec.c
==============================================================================
--- trunk/libavcodec/alsdec.c Tue Feb 16 15:33:13 2010 (r21848)
+++ trunk/libavcodec/alsdec.c Tue Feb 16 15:48:01 2010 (r21849)
@@ -192,6 +192,7 @@ typedef struct {
unsigned int frame_id; ///< the frame ID / number of the current frame
unsigned int js_switch; ///< if true, joint-stereo decoding is enforced
unsigned int num_blocks; ///< number of blocks used in the current frame
+ unsigned int s_max; ///< maximum Rice parameter allowed in entropy coding
uint8_t *bgmc_lut; ///< pointer at lookup tables used for BGMC
unsigned int *bgmc_lut_status; ///< pointer at lookup table status flags used for BGMC
int ltp_lag_length; ///< number of bits used for ltp lag value
@@ -720,9 +721,9 @@ static int read_var_block_data(ALSDecCon
if (opt_order)
bd->raw_samples[0] = decode_rice(gb, avctx->bits_per_raw_sample - 4);
if (opt_order > 1)
- bd->raw_samples[1] = decode_rice(gb, s[0] + 3);
+ bd->raw_samples[1] = decode_rice(gb, FFMIN(s[0] + 3, ctx->s_max));
if (opt_order > 2)
- bd->raw_samples[2] = decode_rice(gb, s[0] + 1);
+ bd->raw_samples[2] = decode_rice(gb, FFMIN(s[0] + 1, ctx->s_max));
start = FFMIN(opt_order, 3);
}
@@ -1508,6 +1509,11 @@ static av_cold int decode_init(AVCodecCo
avctx->bits_per_raw_sample = (sconf->resolution + 1) * 8;
}
+ // set maximum Rice parameter for progressive decoding based on resolution
+ // This is not specified in 14496-3 but actually done by the reference
+ // codec RM22 revision 2.
+ ctx->s_max = sconf->resolution > 1 ? 31 : 15;
+
// set lag value for long-term prediction
ctx->ltp_lag_length = 8 + (avctx->sample_rate >= 96000) +
(avctx->sample_rate >= 192000);
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