#1495: H263+MP3 -> .vob (MPEG2 + AC3) = corrupt audio
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Reporter: grolschie | Type: defect
Status: new | Priority: important
Component: FFmpeg | Version: unspecified
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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I have noticed with recent ffmpeg builds, that converting the low quality
YouTube videos (H263 video with MP3) to AC3 Dolby Digital 2.0 @ 48,000hz
and 44,100hz results in good audio in the right channel, but just digital
noise on the left channel. Here is an example:
-------------------------------
ffmpeg.exe -i "http://o-o.preferred.tnz-akl1.v20.ls
cache7.c.youtube.com/videoplayback?upn=-yli7TGCA4Q&sparams=algorithm%2Cburst%2Cc
p%2Cfactor%2Cid%2Cip%2Cipbits%2Citag%2Csource%2Cupn%2Cexpire&fexp=907048%2C92480
1%2C904102%2C906510%2C911205%2C902519%2C907217%2C907335%2C921602%2C919306%2C9226
00%2C919316%2C920704%2C924500%2C924700%2C913542%2C913547%2C919324%2C907344%2C912
706%2C902518&mt=1340913017&ms=au&algorithm=throttle-
factor&itag=34&ip=219.0.0.0&
burst=40&sver=3&signature=57B4A269E25DC3DB60C3B7E82980F0853F6B362D.D349F29F2208E
B92D7624067EA655BBCF40FE2BC&source=youtube&expire=1340934623&key=yt1&ipbits=8&fa
ctor=1.25&cp=U0hTRVlOUl9HTUNOM19RSFZHOkIxakpzdXlzODA5&id=2e06a02833dcd0e2"
-y -t
hreads 1 -copyts -c:v mpeg2video -qscale 3 -r 30000/1001 -g 15 -c:a ac3
-b:a 384
k -ar 48000 -ac 2 -map 0:0 -map 0:1 -sn -f vob output.vob
ffmpeg version N-42016-gc103dc0 Copyright (c) 2000-2012 the FFmpeg
developers
built on Jun 28 2012 20:16:03 with gcc 4.7.1
configuration: --enable-gpl --enable-version3 --disable-w32threads
--enable-ru
ntime-cpudetect --enable-avisynth --enable-bzlib --enable-frei0r --enable-
libass
--enable-libcelt --enable-libopencore-amrnb --enable-libopencore-amrwb
--enable
-libfreetype --enable-libgsm --enable-libmp3lame --enable-libnut --enable-
libope
njpeg --enable-librtmp --enable-libschroedinger --enable-libspeex
--enable-libth
eora --enable-libutvideo --enable-libvo-aacenc --enable-libvo-amrwbenc
--enable-
libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-
libxvid --e
nable-zlib
libavutil 51. 63.100 / 51. 63.100
libavcodec 54. 29.101 / 54. 29.101
libavformat 54. 11.100 / 54. 11.100
libavdevice 54. 0.100 / 54. 0.100
libavfilter 3. 0.100 / 3. 0.100
libswscale 2. 1.100 / 2. 1.100
libswresample 0. 15.100 / 0. 15.100
libpostproc 52. 0.100 / 52. 0.100
Input #0, flv, from 'http://o-o.preferred.tnz-
akl1.v20.lscache7.c.youtube.com/vi
deoplayback?upn=-yli7TGCA4Q&sparams=algorithm%2Cburst%2Ccp%2Cfactor%2Cid%2Cip%2C
ipbits%2Citag%2Csource%2Cupn%2Cexpire&fexp=907048%2C924801%2C904102%2C906510%2C9
11205%2C902519%2C907217%2C907335%2C921602%2C919306%2C922600%2C919316%2C920704%2C
924500%2C924700%2C913542%2C913547%2C919324%2C907344%2C912706%2C902518&mt=1340913
017&ms=au&algorithm=throttle-
factor&itag=34&ip=219.0.0.0&burst=40&sver=3&signatu
re=57B4A269E25DC3DB60C3B7E82980F0853F6B362D.D349F29F2208EB92D7624067EA655BBCF40F
E2BC&source=youtube&expire=1340934623&key=yt1&ipbits=8&factor=1.25&cp=U0hTRVlOUl
9HTUNOM19RSFZHOkIxakpzdXlzODA5&id=2e06a02833dcd0e2':
Metadata:
starttime : 0
totalduration : 209
totaldatarate : 601
bytelength : 15709754
canseekontime : true
sourcedata : B7A387304HH1340930999438436
purl :
pmsg :
Duration: 00:03:28.52, start: 0.000000, bitrate: 602 kb/s
Stream #0:0: Video: h264 (Main), yuv420p, 480x360 [SAR 1:1 DAR 4:3],
475 kb/
s, 25 tbr, 1k tbn, 50 tbc
Stream #0:1: Audio: aac, 44100 Hz, stereo, s16, 133 kb/s
Please use -q:a or -q:v, -qscale is ambiguous
[graph 0 input from stream 0:0 @ 024c9e80] w:480 h:360 pixfmt:yuv420p
tb:1/1000
fr:25/1 sar:1/1 sws_param:flags=2
[output stream 0:0 @ 02c84200] No opaque field provided
[graph 1 input from stream 0:1 @ 02dadaa0] tb:1/1000 samplefmt:s16
samplerate:44
100 chlayout:0x3
[auto-inserted resampler 0 @ 02c60ee0] chl:stereo fmt:s16 r:44100Hz ->
chl:stere
o fmt:flt r:48000Hz
[vob @ 02be4020] VBV buffer size not set, muxing may fail
Output #0, vob, to 'output.vob':
Metadata:
starttime : 0
totalduration : 209
totaldatarate : 601
bytelength : 15709754
canseekontime : true
sourcedata : B7A387304HH1340930999438436
purl :
pmsg :
encoder : Lavf54.11.100
Stream #0:0: Video: mpeg2video, yuv420p, 480x360 [SAR 1:1 DAR 4:3],
q=2-31,
200 kb/s, 90k tbn, 29.97 tbc
Stream #0:1: Audio: ac3, 48000 Hz, stereo, flt, 384 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (h264 -> mpeg2video)
Stream #0:1 -> #0:1 (aac -> ac3)
Press [q] to stop, [?] for help
frame= 53 fps=0.0 q=3.0 size= 194kB time=00:00:01.70 bitrate=
933.9kbits/s
frame= 97 fps= 96 q=3.0 size= 420kB time=00:00:03.16
bitrate=1085.4kbits/s
frame= 134 fps= 87 q=3.0 size= 632kB time=00:00:04.40
bitrate=1175.5kbits/s
frame= 170 fps=0.0 q=3.0 size= 870kB time=00:00:05.60
bitrate=1271.4kbits/s
frame= 212 fps= 83 q=3.0 size= 1140kB time=00:00:07.00
bitrate=1332.8kbits/s
frame= 250 fps= 82 q=3.0 size= 1342kB time=00:00:08.27
bitrate=1328.6kbits/s
frame= 290 fps= 82 q=3.0 size= 1556kB time=00:00:09.60
bitrate=1326.5kbits/s
frame= 325 fps= 81 q=3.0 Lsize= 1780kB time=00:00:10.81
bitrate=1348.8kbits/
s dup=54 drop=0
video:1243kB audio:508kB subtitle:0 global headers:0kB muxing overhead
1.632107%
----------------------------------
Here is the resulting file:
https://sites.google.com/site/grolschie/output.vob
The noise is quite loud and possibly bad for speakers.
Strangly, converting to 22050hz audio seems fine though.
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1495>
FFmpeg <http://ffmpeg.org>
FFmpeg issue tracker
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