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Rich Felker | 1 Oct 02:29

Re: A-V sync

On Sun, Sep 30, 2007 at 11:48:33PM +0200, pehache-tolai wrote:
> Well, maybe you're right, but I'm not sure. My english is definitely not 
> perfect, but from the text below I would still vote for my interpretation:
> 
> ----------------------------------------
> `-async samples_per_second'
> Audio sync method. "Stretches/squeezes" the audio stream to match the 
> timestamps, the parameter is the maximum samples per second by which the 
> audio is changed.
> ----------------------------------------
> 
> Changing the audio /by/ n samples per second means to me that 1 sec of audio 
> (48000 samples for instance) is resampled so as to last more or less than 1 
> sec. (48000 +/- n samples), with n <= samples_per_second

OK, here’s a technical explanation. In most formats, audio packets
have timestamps, either explicitly or implicitly via a nominal
samples-per-packet or samples-per-second header in the container.
However, there’s also an actual number of samples stored in each
packet, and this might or might not match the packet duration as
determined by the timestamps.

My understanding is that the -async option corrects this by adaptively
resampling audio packets from whatever samplerate the packet actually
has (computed from its start and end timestamp and number of samples
contained in the frame) to the samplerate specified by the argument to
-async.

Rich
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mike | 1 Oct 02:24
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Re: A-V sync

On Sun, 2007-09-30 at 23:48 +0200, pehache-tolai wrote:
> "mike" <mike <at> redtux.org.uk> a crit dans le message de news:
> 1191156926.15998.10.camel <at> localhost.localdomain
> 
> >
> > You are in error I believe
> >
> > -async 1 synchronises the streams at the start of encoding
> 
> OK
> 
> > -async >1 sets the number of audio samples every second, nothing to
> > with adding or removing samples. Basically if you have -async 24
> > (which I use) 24 times a second ffmpeg resamples and syncs audio to
> > the video stream
> 
> Well, maybe you're right, but I'm not sure. My english is definitely not 
> perfect, but from the text below I would still vote for my interpretation:
> 
> ----------------------------------------
> `-async samples_per_second'
> Audio sync method. "Stretches/squeezes" the audio stream to match the 
> timestamps, the parameter is the maximum samples per second by which the 
> audio is changed.
> ----------------------------------------
> 
> Changing the audio /by/ n samples per second means to me that 1 sec of audio 
> (48000 samples for instance) is resampled so as to last more or less than 1 
> sec. (48000 +/- n samples), with n <= samples_per_second
>
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Josh Millstein | 1 Oct 04:23

Unkown encoder mp3 and suitable output format jpg

Hello.  I've been trying to install ffmpeg but can't get it to work
properly.  

I have the following php test file:

$videoName = "11911872259112743930253.20023Movie.mov";
$outputName = "tst.flv";
$outputThumb = "tst.jpg";

$origPath = "ffmpeg -i ./files/$videoName -s 400x300 -qscale 4 -acodec mp3
-ar 44100 -r 15 ./files/$outputName";
$thumbPath = "ffmpeg -i ./files/$videoName -ss 00:00:03 -t 00:00:01 -s 80x60
-r 1 ./thumbs/$outputThumb";

exec($origPath);
exec($thumbPath);

When I run it I get the following response.

The Key problem being output below is --> ( Unknown encoder 'mp3', and
Unable to find a suitable output format for './thumbs/tst.jpg')

FFmpeg version SVN-r10629, Copyright (c) 2000-2007 Fabrice Bellard, et al.
  configuration: --enable-libmp3lame --enable-libogg --enable-libvorbis
--disable-mmx --enable-shared
  libavutil version: 49.5.0
  libavcodec version: 51.44.0
  libavformat version: 51.14.0
  built on Sep 30 2007 16:06:27, gcc: 4.1.1 20070105 (Red Hat 4.1.1-52)
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Scott C. Frase | 1 Oct 04:51
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ffmpeg should be multithreading but is not

Hi,
New user to this list.  

It seems I should be running multithreaded, but I am not seeing this and
wondering why.  Here's my situation:

I am running Fedora Core 6, 64-bit (x86-64) on a Dell SC1430 dual quad
core xeon.  I ran this ffmpeg command to convert an MPEG2-TS to DVD:

ffmpeg -i boston_14.m2t -target dvd output.mpg

I saw the task bouncing to individual CPUs, but no multithreading
(different CPUs working on the same task at the same time) occurred.  

Here is the screen output:
[sfrase <at> puter ~]# ffmpeg -i boston_14.m2t -target dvd output.mpg
FFmpeg version SVN-r8876, Copyright (c) 2000-2007 Fabrice Bellard, et
al.
  configuration: --prefix=/usr --incdir=/usr/include/ffmpeg
--libdir=/usr/lib64 --shlibdir=/usr/lib64 --mandir=/usr/share/man
--arch=x86_64 --extra-cflags=-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2
-fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64
-mtune=generic --enable-libmp3lame --enable-libogg --enable-libtheora
--enable-libvorbis --enable-libfaad --enable-libfaac --enable-libgsm
--enable-xvid --enable-x264 --enable-liba52 --enable-liba52bin
--enable-libdts --enable-pp --enable-pthreads --disable-static
--enable-shared --enable-gpl --disable-debug --disable-opts
--disable-strip
  libavutil version: 49.4.0
  libavcodec version: 51.40.4
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Josh Millstein | 1 Oct 07:52

Re: Unkown encoder mp3 and suitable output format jpg

> Hello.  I've been trying to install ffmpeg but can't get it to work
> properly.  
> 
> I have the following php test file:
> 
> $videoName = "11911872259112743930253.20023Movie.mov";
> $outputName = "tst.flv";
> $outputThumb = "tst.jpg";
> 
> $origPath = "ffmpeg -i ./files/$videoName -s 400x300 -qscale 4 -acodec mp3
> -ar 44100 -r 15 ./files/$outputName";
> $thumbPath = "ffmpeg -i ./files/$videoName -ss 00:00:03 -t 00:00:01 -s 80x60
> -r 1 ./thumbs/$outputThumb";
> 
> exec($origPath);
> exec($thumbPath);
> 
> When I run it I get the following response.
> 
> The Key problem being output below is --> ( Unknown encoder 'mp3', and
> Unable to find a suitable output format for './thumbs/tst.jpg')
> 
> FFmpeg version SVN-r10629, Copyright (c) 2000-2007 Fabrice Bellard, et al.
>   configuration: --enable-libmp3lame --enable-libogg --enable-libvorbis
> --disable-mmx --enable-shared
>   libavutil version: 49.5.0
>   libavcodec version: 51.44.0
>   libavformat version: 51.14.0
>   built on Sep 30 2007 16:06:27, gcc: 4.1.1 20070105 (Red Hat 4.1.1-52)
>
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Lukas Ruetz | 1 Oct 10:36
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Re: ffmpeg should be multithreading but is not

Hi,

Am Montag, 1. Oktober 2007 04:51 schrieb Scott C. Frase:
> Hi,
> New user to this list.
>
> It seems I should be running multithreaded, but I am not seeing this and
> wondering why.  Here's my situation:
>
> I am running Fedora Core 6, 64-bit (x86-64) on a Dell SC1430 dual quad
> core xeon.  I ran this ffmpeg command to convert an MPEG2-TS to DVD:
>
> ffmpeg -i boston_14.m2t -target dvd output.mpg
>
> I saw the task bouncing to individual CPUs, but no multithreading
> (different CPUs working on the same task at the same time) occurred.
>
> Here is the screen output:
> [sfrase <at> puter ~]# ffmpeg -i boston_14.m2t -target dvd output.mpg
> FFmpeg version SVN-r8876, Copyright (c) 2000-2007 Fabrice Bellard, et
> al.
>   configuration: --prefix=/usr --incdir=/usr/include/ffmpeg
> --libdir=/usr/lib64 --shlibdir=/usr/lib64 --mandir=/usr/share/man
> --arch=x86_64 --extra-cflags=-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2
> -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64
> -mtune=generic --enable-libmp3lame --enable-libogg --enable-libtheora
> --enable-libvorbis --enable-libfaad --enable-libfaac --enable-libgsm
> --enable-xvid --enable-x264 --enable-liba52 --enable-liba52bin
> --enable-libdts --enable-pp --enable-pthreads --disable-static
> --enable-shared --enable-gpl --disable-debug --disable-opts
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Michel Bardiaux | 1 Oct 10:52
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Re: Mixing two audio files to one output

skye klein a écrit :
> Hi, Relatively new to ffmpeg, but getting along pretty well. Hoping
> someone can shed some light on multiple audio input files -> one
> (mixed) output.
> 
> Closes I've been able to get is: ffmpeg -i sound1.wav -i sound2.wav
> output.wav -newaudio
> 
> Which works, (see below) but strangely 

Not strangely, that is the normal behavoiur. ffmpeg does not support 
audio mixing (nor real video mixing, for that matter).

> the output file is twice as
> long as the inputs (which as both identical length / bitrate /
> channels etc) and plays back "choppily" as if there's some kind of
> framerate issue.
> 
> (I have tries SoX, which works great, but I'm developing this for
> online deployment and haven't found any webhost which offer SoX
> access.)
> 
What do you mean by 'sox access'? If you can install and run ffmpeg, you 
can install and run sox.

Always post the *complete* output messages, not an edited version. You
dont know what might be relevant.

Greetings,
--

--
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aviad rozenhek | 1 Oct 13:04
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decoding packets

On Sun, Sep 30, 2007 at 07:56:14PM +0200, aviad rozenhek wrote:
>> update:
>> by using the extradata I have from method #2, I am able to decode video.
>> the question remains how to generate this extradata?

>I really thing this belongs to the -users list, but either way it would
>be much easier to help if you had printed the extradata in hex instead
>of base64. I seriously doubt anyone here can read base64 natively.
Sorry about base64 encoding, here is the culprit in hex:
Good extradata:

extradata = 14d4033ffe1013274d4033a918283f60d4180418c2b5ef7c04010428ce988
extradata_size = 34

Bad extradata:

extradata =
04d03331013274d4033a918283f60d4180418c2b5ef7c04010428ce988
extradata_size = 34

as I mentioned before, the "good" extradata is obtained from ffplay.
the "bad" extradata is generated by yours truly according to
instructions from http://haali.cs.msu.ru/mkv/codecs.pdf

I am interested to know what is the proper way to construct the extradata.
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saqib butt | 1 Oct 13:15
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getting audio/video file information using "ffmpeg" or "mplayer" or "mencoder"

hi

kindly tell me please how can i get complete information about
AUDIO/VIDEO FILE "Resolution",  "bits", "time duration" etc, using ffmpeg or
any other mplayer/mencoder.

i will be really grateful to u, if u kindly grant me the favor.

regards,

--

-- 
+------------------------------------------------ +
|   Name:                               Saqib Butt   |
|   Email:                  mr.saqi <at> gmail.com   |
|   Cell:                     [0092]3024068471  |
+------------------------------------------------ +
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Michel Bardiaux | 1 Oct 13:47
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Re: getting audio/video file information using "ffmpeg" or "mplayer" or "mencoder"

saqib butt a écrit :
> hi
> 
> kindly tell me please how can i get complete information about
> AUDIO/VIDEO FILE "Resolution",  "bits", "time duration" etc, using ffmpeg or
> any other mplayer/mencoder.
> 
> i will be really grateful to u, if u kindly grant me the favor.
> 
> regards,
> 
ffmpeg -i

--

-- 
Michel Bardiaux
R&D Director
T +32 [0] 2 790 29 41
F +32 [0] 2 790 29 02
E mailto:mbardiaux <at> mediaxim.be

Mediaxim NV/SA
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Brussel 1160 Bruxelles
http://www.mediaxim.com/
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