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Reconstructing Gapless Playback Info in WMA
dsimcha
post Apr 2 2010, 15:19
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I have some WMA files from a live album (where lack of gapless is noticable and annoying). Somehow (I don't know how) the information necessary for gapless playback was damaged or never recorded properly, so these files play back with a small gap. I assume that gapless on WMA works roughly the same way as it does on MP3, i.e. a tag tells the decoder how many padding samples to ignore in the last frame. Is there any utility that can reconstruct this information by assuming any continuous run of zeros at the end of the last frame is padding?
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timcupery
post Apr 2 2010, 19:04
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I'm not aware that a gapless-info system exists for WMA. Although I may be wrong, as WMA is not something I follow very closely.
If you want to make it into a gapless CD, you can convert the WMA files to wav, trim leading and ending silence (and it won't be all actual zero-sample silence, so you'll need to look at the wavform), and then burn to an audio CD.


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dsimcha
post Apr 2 2010, 19:26
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QUOTE (timcupery @ Apr 2 2010, 14:04) *
I'm not aware that a gapless-info system exists for WMA. Although I may be wrong, as WMA is not something I follow very closely.
If you want to make it into a gapless CD, you can convert the WMA files to wav, trim leading and ending silence (and it won't be all actual zero-sample silence, so you'll need to look at the wavform), and then burn to an audio CD.


On second thought I guess that compression artifacts would prevent the padding from being all zeros. I would be willing to do this manually, since we're only talking about ~20-30 files. I just need a way that doesn't involve transcoding.
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timcupery
post Apr 2 2010, 19:30
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QUOTE (dsimcha @ Apr 2 2010, 14:26) *
On second thought I guess that compression artifacts would prevent the padding from being all zeros. I would be willing to do this manually, since we're only talking about ~20-30 files. I just need a way that doesn't involve transcoding.

Again, I think the only way to do this that "doesn't involve transcoding" (at least not to another lossy source) is to decode, clean the beginning and end "silence" from the wav file, and keep it as wav or FLAC.
Or just spring for the CD or Lame-encoded mp3's, as the monetary value on your time is probably worth more than what you'd pay for the CD or mp3's with gapless info.


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benski
post Apr 2 2010, 20:49
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gapless encoding is built into the WMA format. I'm not sure if ffmpeg-based players read the data or not. I *believe* it's stored at the end of the file because that's where other codec-related config data is stored.
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dsimcha
post Apr 8 2010, 18:02
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QUOTE (benski @ Apr 2 2010, 15:49) *
gapless encoding is built into the WMA format. I'm not sure if ffmpeg-based players read the data or not. I *believe* it's stored at the end of the file because that's where other codec-related config data is stored.


I actually found out that the problem was foobar2000, not the files. Gapless works in Windows Media Player.
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