transcode aac stream to mp3 stream on-the-fly

[hakova]

Hi there,

What I aim to achieve is transcoding an aac stream to an mp3 one, preferably using a big enough cache to avoid problems. I will then play the mp3 stream on my receiver, which fails to play the aac stream. A command line solution is preferred to a description of how to do this by using the GUI, although I will happily take whatever can be provided.

I tried the following with no success:

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vlc -vvv http://xx.xx.xxx.x:8875/ --sout-transcode-acodec 'mp3' --sout-transcode-ab 192 --sout-transcode-channels 2 --sout-standard-access 'http' --sout-standard-mux 'raw' --sout-standard-dst '8091'

I am using Mandriva 2008.0 with vlc 0.8.6c.

Regards,

Hakan

[Arite]

Try for example:

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vlc -vvv http://xx.xx.xxx.x:8875/ --sout #transcode{acodec=mp3,ab=192,channels=2}:duplicate{dst=std{access=http,mux=raw,dst=DEST_IP:8091}}

Where DEST_IP is your destination IP address (receiver IP address).

Arite.

[hakova]

Thanks Arite for your quick reply. It works, but with a strange twist. The stream is 22050 Hz instead of 44100, and probably because of that the playback is like listening to a 1/2 of normal playback rate, which sounds like slow motion. Now if you have a vlc client listening to this stream, you can double the playback rate there and listen to it at normal rate, but my receiver cannot increase the playback rate unfortunately. Is there any way to enforce a transcoding/sampling frequency of 44100 Hz? Or is there any other solution to this problem that you can think of?

Regards,

Hakan

Edit: I added the following to the transcode section of the command line:

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samplerate=44100

Unfortunately, everything is still in slow motion on the client side, although now the sample rate reads 44100 instead of 22050. It must be something else than the sampling rate.

[hakova]

OK, after searching quite a bit, I figured that there have been other users with similar experience. There was also a bug report (#1630) about a similar issue, although not quite the same. That bug report was then closed with an update note of a newer version. Therefore, I tried the same command line on vlc 0.9.3 Grishenko, which just produced noise instead of a real audio stream. The slow audio problem was at least solvable when one used vlc client on the other end by multiplying the playback rate; whereas noise is not. Therefore, it seems like version 0.9.3 was a step backward on this aspect.

A workaround for this issue might be transcoding the mp4/aac stream to a local mp3 file and then streaming from it, instead of doing it on the fly. In this case scenario, there has to be a certain delay in playback (which is fine) and a file size limit to avoid using valuable HDD space in GBs. Can any one point me to the right direction of how to rotate local mp3 file(s)? For example, if I have 3 mp3 files used as some kind of a cache, the first one gets deleted as the third one is created and written to, and the second one will be played back. Then second one then will be rotated to the first one once the playback finishes, the third one will become the second one and therefore will start to be played back, while a new third mp3 file will be written synchronously. I just don't have the required programming background to put something together like this, and any help will be greatly appreciated.

Hakan

[Osman]

Hi,
I'm trying to transcode an AAC 32k 44.1kHz stereo shoutcast stream into MP3 12k8kHz 44.kHz stereo.
So far, using info from this thread, I've got it transcoding into MP3 128kHz 44.kHz mono.
I just can't seem to get stereo to work. I've included 'channels=2', but this is not making any difference.
Any ideas?

[hakova]

...
So far, using info from this thread, I've got it transcoding into MP3 128kHz 44.kHz mono....

Hi Osman,

May I ask what operating system and which version of vlc you are using?

[Osman]

Hi,
I'm using 0.9.9 (the latest version which I downloaded the other day).
This has a lot of problems fixed, and leaves only this mono issue.
Prior to this, version 0.9.8 did not work well at all and was literally unusable.
If you can help/advise, it would be greatly appreciated.
Thanks,
Osman

[Jean-Baptiste Kempf]

Yeah, 1.0.0 has more issues fixed.

[Osman]

I've tried the latest 1.0.0 from the nightlies area, but this isn't working either
I'm pretty sure I've got the config right, and this is a functionality problem within the player.
Unless anyone knows how to overcome this problem, I'm guessing it's going to be a case of waiting until a release comes out which has the fix.
I wait in hope and patience...
Osman