[FFmpeg-devel] [PATCH v2 18/19] fate/matroska: Test remuxing tracks for hearing/visually impaired

[Andreas Rheinhardt]

Carl Eugen Hoyos:
> Am Sa., 20. Feb. 2021 um 17:00 Uhr schrieb Andreas Rheinhardt
> <andreas.rheinhardt at gmail.com>:
>>
>> The tests also test the other dispositions: commentary, descriptions
>> as well as dub and original language.
>>
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
>> ---
>> The first version of the matroska-wtv-remux test used the fixed-point
>> mp2 decoder; given that no floats are involved I presumed that this
>> would give reproducible results among different arches. I was wrong [1].
> 
> How is this possible?
> 
I just had a second look and I think I was wrong about the culprit. Here
is the diff from ppc from Andriy:

-1206b022950477c92c2313a1fa11143b
*tests/data/fate/matroska-wtv-remux.matroska
+95d7ff43421e95554fb50c02e5b09e5e
*tests/data/fate/matroska-wtv-remux.matroska
 752499 tests/data/fate/matroska-wtv-remux.matroska
 #extradata 0:        5, 0x001c0014
 #extradata 1:       22, 0x12dc010c
@@ -46,7 +46,7 @@
 1,        144,        144,       24,      576, 0x422e12bd
 4,        144,        144,       24,     6912, 0xfccb037f
 2,        163,        163,       24,      192, 0xc948791d
-3,        163,        163,        0,       19, 0x09f10390
+3,        163,        163,        0,       19, 0x2e110794
 1,        168,        168,       24,      576, 0xa7581b29
 4,        168,        168,       24,     6912, 0xa650ad97
 2,        187,        187,       24,      192, 0xc948791d
Test matroska-wtv-remux failed. Look at
tests/data/fate/matroska-wtv-remux.err for details.
tests/Makefile:255: recipe for target 'fate-matroska-wtv-remux' failed
make: *** [fate-matroska-wtv-remux] Error 1

Stream 3 is the hearing impaired stream. It is also completely blank
(consists only of zeroes after decoding); stream 4 is the ordinary audio
track (also mp2) decoded to pcm_24be. There is no dif for it. So it
seems to be the alac encoder, something which I had not considered
previously because this is a lossless encoder. But now I looked and
there are doubles in ff_lpc_calc_coeffs, but this code is only used if
compression_level == 2 (the default). I will give this another try by
setting it to 1.

- Andreas