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[SOLVED] No sound in ipod after ffmpeg conversion
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dohko
Tux's lil' helper
Tux's lil' helper


Joined: 24 Sep 2004
Posts: 112
Location: São Paulo - Brasil

PostPosted: Sat Jul 28, 2007 2:19 pm    Post subject: [SOLVED] No sound in ipod after ffmpeg conversion Reply with quote

Hello fellows!

I got a video ipod and I hadn't been converting avi videos to it for some time, say 3 months or so. Yesterday I encoded one using my usual ipod video encode script. After I uploaded it to the ipod, there was no sound in the movie.

Here is the script I use to encode videos:

Code:
#!/bin/sh -f
## ipodvidenc - The iPod Video Encoder for Linux.
## Created by Eric Hewitt, January 9, 2006.
## Released under the GPL.  Go nuts.
## Modified by Chous to add Usage function and interactiveless parameters.
function usage {
cat <<EOF
$0 inputFile outputFile
where
    inputFile: The video to convert
    outoutFile: The output video
EOF
exit 1
}

[ $# -lt 2 ] && usage

_o=`echo $2 | awk -F"." '{if  (NF > 1) for (i=1; i<NF; i++) {printf("%s", $i); if (i != NF-1) { printf(".");}} else print $0
;}'`

ffmpeg -i "$1" -f mp4 -vcodec mpeg4 -maxrate 2000 -b 1500 -qmin 3 -qmax 5 \
-bufsize 4096 -g 300 -acodec aac -ar 44100 -ab 192 -s 320x240 -aspect 16:9 "$_o.mp4" \
2>/dev/null


I googled for this problem and searched the forum, but without any luck. So, I started tackling the problem to see if I could find a reasonable path to follow. Here are my thoughts:

1. The avi file or the converted mp4 file are somehow corrupted
-> I discarded this because the avi and the mp4 files play fine under mplayer, with the audio being perfectly functional and synchronized with the video. Also, another file I converted ended up in the same situation (I really don't think I'm in such a bad luck to have two corrupted files :-) ).

2. Gtkpod is messing something up during the upload
-> Discarded because I retrieved one the the mp4 videos from my ipod and uploaded it again, and it worked perfectly.

3. Changes to ffmpeg caused by an upgrade. Now, there are two possible scenarios for this:

3a. Upgrade in ffmpeg had something changed in its aac coded that made the ipod stop being able to decode the audio layer of the mp4 file.
-> Suggestions on how to test this? The files I'm converting to mp4 play well in mplayer.

3b. Upgrade of something that ffmpeg depends on made ffmpeg work differently.
-> Well, perhaps an upgrade to glibc... then I should try to recompile ffmpeg and see if I get anywhere by doing that.

4. Ideas?

I'll be working on this... if somebody has any suggestion here, it would be appreciated.

Thanks!


Last edited by dohko on Sat Jul 28, 2007 3:19 pm; edited 1 time in total
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dohko
Tux's lil' helper
Tux's lil' helper


Joined: 24 Sep 2004
Posts: 112
Location: São Paulo - Brasil

PostPosted: Sat Jul 28, 2007 3:18 pm    Post subject: Reply with quote

Hi guys,

I was checking my emerge logs, and here's what I found out:

Code:
1185457143: Started emerge on: Jul 26, 2007 10:39:03
1185457143:  *** emerge --ask --verbose faac
1185457151:  >>> emerge (1 of 1) media-libs/faac-1.25 to /


This is the AAC codec library. So, this led me to follow path 3b. I recompiled ffmpeg and voala, my ipod can play the converted mp4 audio now. It looks like that something changed in faac that requires ffmpeg to be recompiled in order for it to properly use whatever is new in faac.

Hope this helps more people.

Thanks!
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antlers
n00b
n00b


Joined: 10 May 2008
Posts: 1

PostPosted: Sat May 10, 2008 8:33 pm    Post subject: Reply with quote

dohko wrote:
Hi guys,

I was checking my emerge logs, and here's what I found out:

Code:
1185457143: Started emerge on: Jul 26, 2007 10:39:03
1185457143:  *** emerge --ask --verbose faac
1185457151:  >>> emerge (1 of 1) media-libs/faac-1.25 to /


This is the AAC codec library. So, this led me to follow path 3b. I recompiled ffmpeg and voala, my ipod can play the converted mp4 audio now. It looks like that something changed in faac that requires ffmpeg to be recompiled in order for it to properly use whatever is new in faac.

Hope this helps more people.

Thanks!


Thank you very much. This is just what I needed to know.
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