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Topic: Low-bitrate MP3 won't play in v0.9.2 (Read 3429 times) previous topic - next topic
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Low-bitrate MP3 won't play in v0.9.2

Several days ago, I converted some FLAC files to low-bitrate MP3s using foobar 0.9.2. However, it seems that most of the files are not playable in v0.9.2. The play just fine in v0.8.3 and in other my other audio players (e.g., 1by1 and XMPlay). When I try to play them, I get this error: "Decoding failure at 0:01.571 (Unsupported format or corrupted file)."

Here is the file info from one of the files:

Quote
enc_delay = 576
enc_padding = 1472
mp3_accurate_length = yes
bitrate = 29
codec = MP3
encoding = lossy
channels = 1
samplerate = 11025
extrainfo = VBR
mp3_stereo_mode = mono
tagtype = id3v2
----------
808960 samples @ 11025Hz
File size: 266 240 bytes

The file is currently available for download.

Thank you much for your time.

Low-bitrate MP3 won't play in v0.9.2

Reply #1 –
It's gotta be bug in foobar. It seems proper MP3 to me.

Could you use LAME 3.97b2 instead of 3.96.1, and use the same config and then encode again? I'm just curious to see that does foobar fail again.

Low-bitrate MP3 won't play in v0.9.2

Reply #2 –
Bitrate index > 8 is not allowed for MPEG-2.5, so it's a bug in LAME not in foobar.

Low-bitrate MP3 won't play in v0.9.2

Reply #4 –
Same doc as the previous bug in LAME
The only reasonable document with MPEG-2.5 described in it: "MPEG Layer3 Bitstream Syntax andDecoding.doc" on page 17.

Low-bitrate MP3 won't play in v0.9.2

Reply #5 –
Once again, I do not fully trust this doc (layer 3 bitstream syntax and decoding), as even FhG encoders do not conform to this (at least regarding actual frame sizes, max frame size, max main_data_begin value).

We should try this file with an FhG decoder. If FhG decodes this, then I'd say that it's compliant regarding mpeg 2.5.

Low-bitrate MP3 won't play in v0.9.2

Reply #6 –
Of course they decode it, otherwise you would have heard something about this before. The interesting question is if you can get an FhG encoder to create such files.

Low-bitrate MP3 won't play in v0.9.2

Reply #7 –
Tested with mp3enc 3.1:

8000Hz file encoding to 64 kbps: works
Command line used: >mp3encdemo31.exe -if castanets8_mono.wav -of castanets8_mono.mp3 -esr 8000.0 -br 64000

8000Hz file encoding to 80 kbps: doesnt work
Command line used: >mp3encdemo31.exe -if castanets8_mono.wav -of castanets8_mono.mp3 -esr 8000.0 -br 80000

Funnily enough it errors out saying the bitrate is too low

Low-bitrate MP3 won't play in v0.9.2

Reply #8 –
mp3enc is bailing out (bitrate too low??) , l3enc does not work anymore, mp3sencoder is resampling to higher sampling rate, ACM only offers specific configurations.

So no, I can't produce such files with FhG encoders. (but FhG decoders are decoding this fine)
Perhaps we should restrict mpeg 2.5 to 64kbps. On the other hand, every decoder (except new Foobar) handles this.