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  • Digital-8 sound takes enormous time to compress in Compressor

  • Ross Norton

    December 23, 2008 at 4:54 pm

    hi all,

    My first post here; as ’til-now lurker, am very impressed with the quality of community and mutual suport I’ve seen here @ CreativeCow !

    Here’s something I hope folks her may be able to shed some light on:

    I’m editing some old Hi-8 (yes, Hi-8) footage for a friend in FCS2 (ie. v 6.0.4).

    We digitized this earlier this year by putting the analog tapes into a subsequent model Sony Digital-8 camera, and capturing the footage into Final Cut Studio HD (ie. v 5.x).

    Editing and grading has all gone smoothly, but I’m _still_ experiencing a problem that happened first time I helped my friend out:

    audio takes _ages_ to compress in Compressor – most recently (this morning) estimated over 6 hours to encode 64 minutes of simple on-camera audio to standard Dolby stereo for DVD.

    Usually when I send DV, HDV, or HDCAM EX sequences to Compressor, the audio is the fastest-running component to be compressed, but in this case, audio is taking far longer than video to compress.

    My sequence is set to 32 kHz audio (the source file sampling rate), I’ve rendered all the audio (no idea why it even _needs_ to be rendered, but I figured that this might be the cause of this same bottleneck I’ve experienced before).

    Compressor won’t allow me to create a .ac3 (ie. Dolby) setting with a 32 kHz sample rate (it’s grayed out), and if I try to make a setting for AIFF audio, I can’t set floating point unless I up the sample size to 32 bit.

    Though QuickTime Pro (and the properties pop-up in Final Cut) report the source files as 32 kHz 32-bit, I understand (and VideoLAN Client reports) that the source files are in fact at a 16-bit sample size.

    Though it will cut into space I have for video on the final DVD, sans any help here, my next tactic will be trying AIFF as described above – but this seems no more promising than other things I’ve tried.

    Perhaps I have to use 48 kHz audio in sequence settings, then render audio at this rate before sending to Compressor, even though this runs counter to advice to have one’s sequences at the native settings of the source files. Too, this may just move the same enormous delay to the audio rendering stage – I fail to see why this should be such a big hairy deal.

    Any suggestions/past experience with this amongst fellow Creative Cows here?

    I need help – I have another, longer DVD to compress for Christmas present delivery tomorrow morning December 24, and I fear this *#[email protected]%#^$ may mess up my ability to have this done on time.

    many thanks for any and all assistance,


    MacBook Pro 2 GHz Core Duo 2 GB RAM, 320 GB Seagate 7200 RPM internal drive, 500 & 750 GB Seagate eSATA external drives
    Final Cut Pro 6.0.4, Color 1.0.2, Compressor 3.0.3

  • Bill Dewald

    December 23, 2008 at 5:32 pm

    32kHz audio causes nothing but headache.

    You instinct was right – transcode to 48kHz on the timeline. That should help.

  • Ross Norton

    December 23, 2008 at 10:58 pm

    Thanks Bill, have done that – now running grading in Color and hope to see heck of a lot faster encoding in Compressor tonight.

    If this turns out to be so, I think it shows a weakness in Compressor, in that it would be a great deal slower than FCP in converting 32 kHz sound to 48 kHz sound.

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