generic-library/ffmpeg
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

aacenc_tns: disable coefficient compression by default

Browse Source 
Too much effort and work has been spent on such a simple function.
It simply refuses to work as the specifications say, the
transformation is NOT lossless and creates some crackling and
distortions.
Therefore disable it by default and add a couple of warnings to
scare people away from touching it or wasting their time the
way I did.
This commit is contained in:
Rostislav Pehlivanov 2015-10-17 10:55:19 +01:00
parent 8d18d28918
commit f3ad901a32
1 changed files with 15 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
libavcodec/aacenc_tns.c
View File

@ -31,27 +31,31 @@
#include "aacenc_utils.h"
#include "aacenc_quantization.h"
/*
* Shifts the values as well if compression is possible.
*/
/* Define this to save a bit, be warned decoders can't deal with it
* so it is not lossless despite what the specifications say */
// #define TNS_ENABLE_COEF_COMPRESSION
static inline int compress_coeffs(int *coef, int order, int c_bits)
{
int i, res = 0;
int i;
const int low_idx = c_bits ? 4 : 2;
const int shift_val = c_bits ? 8 : 4;
const int high_idx = c_bits ? 11 : 5;
#ifndef TNS_ENABLE_COEF_COMPRESSION
return 0;
#endif /* TNS_ENABLE_COEF_COMPRESSION */
for (i = 0; i < order; i++)
if (coef[i] < low_idx || coef[i] > high_idx)
res++;
if (res == order)
for (i = 0; i < order; i++)
coef[i] -= (coef[i] > high_idx) ? shift_val : 0;
return res == order;
if (coef[i] >= low_idx && coef[i] <= high_idx)
return 0;
for (i = 0; i < order; i++)
coef[i] -= (coef[i] > high_idx) ? shift_val : 0;
return 1;
}
/**
* Encode TNS data.
* Coefficient compression saves a single bit per coefficient.
* Coefficient compression is simply not lossless as it should be
* on any decoder tested and as such is not active.
*/
void ff_aac_encode_tns_info(AACEncContext *s, SingleChannelElement *sce)
{