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no crisis, just curious about problems with high data rate for audio
After doing dozens of similar shows with this workflow I had a weird problem:
The audio (.mp2 file) for a 7 minute show came in as a one-second piece! Its type wa “not recognized” and the duration was one second and change. (The actual duration of the actual audio file was 7 minutes, and it played fine in Media Player.)
A smart friend recommended that I lower the audio data rate on my Digital Rapids card to 112 Kbps from the original 224 or 256, and Encore accepted the resulting file without problem.
The weird part is that I think I’ve done dozens of shows with this high audio data rate and they were fine.
Any insights as to what is actually happening?
Thanks!
— Bob Cole
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8 Replies
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Bob,
I don’t know why this is happening, but if at all possible try to avoid using MPEG-1 Layer II audio as source. It is better to import an uncompressed PCM, 48KHz, 16 bit audio file and let Encore convert it to Dolby Digital (AC3) at 192 or 224Kb/s.
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[Roadkill] “It is better to import an uncompressed PCM, 48KHz, 16 bit audio file and let Encore convert it to Dolby Digital (AC3) at 192 or 224Kb/s.”
Thanks. I tried to follow this advice but ran into a problem.
I captured a file via Digital Rapids card and Stream software, set to PCM audio.
When I tried to import the .pcm file Adobe Encore wouldn’t recognize it.
What am I doing that Encore dislikes?
— BC
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Bob,
I think encore wants to see a .wav file. Maybe the DR card is simply using .pcm instead of wav as the file extension type. Try changing the file extension to wav and see what encore does with it.
Dave
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Dave, I tried that. Encore saw through my evil plan immediately, and said “File may be corrupt or the file type not supported.”
I’ve been using MPEG Layer II Audio successfully, but every now and then Encore gives me an odd error message that NTSC wants PCM (or something else, I can’t recall right now).
My Digital Rapids software gives me only two choices: MPEG Layer II and PCM. Why won’t Encore accept my PCM files?
— BC
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[Bob Cole] “Why won’t Encore accept my PCM files? “
A very good question. I assume they are 16bit @ 48KHz. I would be curious to look at one of these. If you want, email a short one to me at davef at davefriend dot com.
Have you tried to transcode them to wav files using the DR Stream software?
Dave
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More data:
I encoded via the Digital Rapids card, MPEG Layer II audio, 192 Kbps audio bitrate.
Attempted to import as Timeline into Encore. Encore accepted the files but told me (as before, first post) that the audio file was only a little over a second in length.
So I renamed the audio file’s extension from .mp2 to .wav. Encore accepted the same file with the new extension.
So here is what works for me:
— an MPEG Layer II audio file, at a lower bit rate (96 Kbps).
— an MPEG Layer II audio file, at a higher bit rate (192), IF I rename the extension to .wav file.
What won’t work, so far, is anything encoded as PCM via the Stream/Digital Rapids path.
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If the Digital Rapids writes a PCM file with .pcm extension it is most likely a “raw PCM” file instead of a “PCM WAV” file. Encore, like most other applications, will accept only the .wav variety which not only has a different extension, but also a different structure.
Failing an option to write a real .wav file directly, you could check the “Tools” section at VideoHelp for a utility to convert from .pcm to .wav. Such a conversion will be lossless.
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Stream has an “advanced settings” area for the Mainconcept mpeg encoder; included is an option to multiplex. (There were no options about bitrate or depth.)
So I chose PCM, selected multiplex, and imported the single a/v multiplexed file into Encore, and it worked.
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