[FFmpeg-trac] #2484(FFmpeg:new): atempo - low accuracy
FFmpeg
trac at avcodec.org
Fri Apr 19 10:54:07 CEST 2013
#2484: atempo - low accuracy
--------------------------------+---------------------------------------
Reporter: bars | Type: defect
Status: new | Priority: normal
Component: FFmpeg | Version: unspecified
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
--------------------------------+---------------------------------------
Summary of the bug: I can't reach an exact length (microseconds). The
precision for atempo can only be specified up to 3 digits (x.xxx).
How to reproduce:
Example test.wav (Duration 00:40:44.864)
To convert from 25 fps to 23.976fps (PAL->NTSC)
(24000/1001)/25=0.959040959041 => atempo=0.959040959041
00:40:44.864 => 00:42:29.407 (407ms) (atempo=0.959040959041)
00:40:44.864 => 00:42:29.407 (407ms) (atempo=0.959)
00:40:44.864 => 00:42:29.407 (407ms) (atempo=0.959999999999)
00:40:44.864 => 00:42:29.407 (407ms) (atempo=0.959111111111)
00:40:44.864 => 00:42:29.407 (407ms) (atempo=24000/25025)
When 0.959040959041 correct length must be at 00:42:29.280 (280ms!)
{{{
ffmpeg -i "test.wav" -y -acodec pcm_s16le -af "atempo=0.959040959041"
"test_atempo.wav"
ffmpeg version N-52233-gee94362 Copyright (c) 2000-2013 the FFmpeg
developers
built on Apr 18 2013 02:55:39 with gcc 4.8.0 (GCC)
configuration: --enable-gpl --enable-version3 --disable-w32threads
--enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r
--enable-gnutls --enable-iconv --enable-libass --enable-libbluray
--enable-libcaca --enable-libfreetype --enable-libgsm --enable-libilbc
--enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb
--enable-libopenjpeg --enable-libopus --enable-librtmp --enable-
libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora
--enable-libtwolame --enable-libvo-aacenc --enable-libvo-amrwbenc
--enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs
--enable-libxvid --enable-zlib
libavutil 52. 26.100 / 52. 26.100
libavcodec 55. 2.100 / 55. 2.100
libavformat 55. 2.100 / 55. 2.100
libavdevice 55. 0.100 / 55. 0.100
libavfilter 3. 56.103 / 3. 56.103
libswscale 2. 2.100 / 2. 2.100
libswresample 0. 17.102 / 0. 17.102
libpostproc 52. 3.100 / 52. 3.100
[wav @ 0000000000329fe0] max_analyze_duration 5000000 reached at 5013333
microseconds
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, wav, from 'test.wav':
Metadata:
encoder : Lavf55.2.100
Duration: 00:40:44.86, bitrate: 1536 kb/s
Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz,
stereo, s16, 1536 kb/s
Output #0, wav, to 'test_atempo.wav':
Metadata:
ISFT : Lavf55.2.100
Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz,
stereo, s16, 1536 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (pcm_s16le -> pcm_s16le)
Press [q] to stop, [?] for help
size= 16642kB time=00:01:28.75 bitrate=1536.0kbits/s
size= 36550kB time=00:03:14.93 bitrate=1536.0kbits/s
size= 46708kB time=00:04:09.11 bitrate=1536.0kbits/s
size= 64952kB time=00:05:46.41 bitrate=1536.0kbits/s
size= 78344kB time=00:06:57.83 bitrate=1536.0kbits/s
size= 96750kB time=00:08:35.99 bitrate=1536.0kbits/s
size= 109712kB time=00:09:45.13 bitrate=1536.0kbits/s
size= 129966kB time=00:11:33.15 bitrate=1536.0kbits/s
size= 144280kB time=00:12:49.49 bitrate=1536.0kbits/s
size= 159015kB time=00:14:08.08 bitrate=1536.0kbits/s
size= 172411kB time=00:15:19.52 bitrate=1536.0kbits/s
size= 188794kB time=00:16:46.90 bitrate=1536.0kbits/s
size= 203688kB time=00:18:06.33 bitrate=1536.0kbits/s
size= 221898kB time=00:19:43.45 bitrate=1536.0kbits/s
size= 234376kB time=00:20:50.00 bitrate=1536.0kbits/s
size= 254330kB time=00:22:36.42 bitrate=1536.0kbits/s
size= 264514kB time=00:23:30.73 bitrate=1536.0kbits/s
size= 284585kB time=00:25:17.78 bitrate=1536.0kbits/s
size= 305369kB time=00:27:08.63 bitrate=1536.0kbits/s
size= 326328kB time=00:29:00.41 bitrate=1536.0kbits/s
size= 342023kB time=00:30:24.12 bitrate=1536.0kbits/s
size= 362457kB time=00:32:13.10 bitrate=1536.0kbits/s
size= 374388kB time=00:33:16.73 bitrate=1536.0kbits/s
size= 391906kB time=00:34:50.16 bitrate=1536.0kbits/s
size= 401618kB time=00:35:41.96 bitrate=1536.0kbits/s
size= 415769kB time=00:36:57.43 bitrate=1536.0kbits/s
size= 431130kB time=00:38:19.35 bitrate=1536.0kbits/s
size= 449682kB time=00:39:58.30 bitrate=1536.0kbits/s
size= 467467kB time=00:41:33.15 bitrate=1536.0kbits/s
size= 478014kB time=00:42:29.40 bitrate=1536.0kbits/s
video:0kB audio:478014kB subtitle:0 global headers:0kB muxing overhead
0.000016%
}}}
Patches should be submitted to the ffmpeg-devel mailing list and not this
bug tracker.
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2484>
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