Subject:Sound Data Loss when converting to m4a

Posted by: GamingGuy

Date:12/9/2015 11:34:00 AM

I'm converting some .wav files to .m4a in Sound Forge for Mac (the latest update as of 12/59/15), and I'm noticing that the amount of audio data in the .m4as (the length of the whole file minus the lengths of the silences at the beginning and end) is actually shorter than the amount of audio data in the .wavs.

In most cases, the difference in length has been negligible (a few milliseconds), but there has been more than one instance where the difference has been above 20 milliseconds, which is quite noticeable.

Anyone else experiencing this? Any plans to fix this if it's a Sound Forge issue?

Subject:RE: Sound Data Loss when converting to m4a

Reply by: Chienworks

Date:2/1/2016 6:27:56 PM

Are you saving the new files with exactly the same sample rate as the originals?

Subject:RE: Sound Data Loss when converting to m4a

Reply by: GamingGuy

Date:2/15/2016 9:52:01 AM

You're right! I was downsampling to 22 in the conversion. When I keep the sample rates the same, the timing problems go away. So the CODEC issue was resolved, but this opens up a new problem since I need to downsample my files:

I put my .wav file in sound forge 2.51, I use the Izotope 64 Bit SRC to convert to 22.050 KHz. I hit the process button, and then my .wav file winds up 20 ms shorter. Any ideas about that?