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  1. hello,

    I have a concert on compact disc and blu ray and like the sound of the compact disc much more than the blu-ray.
    How do I convert the compact disc to the blu-ray speed ? I'm not even shure what fps a compact disc could be. The google search said it could be something like 75 fps.
    However there isn't a command in eac such -75.000 -changeTo24.000 which works and I don't really believe that a regular compact disc runs at that speed.
    thanks in advance for your help
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  2. Audio doesn't have a frame rate. Just change the duration.
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  3. audio files don't use framerates..that term is only for video
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  4. if playtimes are the same, good for you

    but i know br and cd audio usually don't match because the latter is edited to remove unnecessary process..


    could also be cds and videos were shot at different times and venues
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  5. Originally Posted by Gwar View Post
    hello,

    I have a concert on compact disc and blu ray and like the sound of the compact disc much more than the blu-ray.
    How do I convert the compact disc to the blu-ray speed ? I'm not even shure what fps a compact disc could be. The google search said it could be something like 75 fps.
    However there isn't a command in eac such -75.000 -changeTo24.000 which works and I don't really believe that a regular compact disc runs at that speed.
    thanks in advance for your help
    As already pointed - there is no framerate for audio, audio use term samplerate and for CD Audio it is 44100Hz where BD may prefer 48000Hz - so all you need is:
    - at first check audio duration - it should be the same for BD audio track and CD Audio track - if they are not the same then IMHO things begin to be very complex
    - after first step try to add additional audio track to existing one with native CD Audio sample rate
    - if from some reason CD Audio 44100Hz is not accepted then you can resample 44100 to 48000Hz and try to repeat second step (i.e. add additional track)

    If duration is not same then you entering to decision or matching audio with video (align audio with video) or changing duration by "stretch" however this will introduce distortions. I would strongly discourage this approach.
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  6. Member Cornucopia's Avatar
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    You or your Google sources are mixing up figures.

    The "75" refers to the fact that every AudioCD-based sector (aka unit of reading) is 1/75th second. But that just amounts to knowing that every sector that is read, encompasses 588 stereo samples (75 * 588 = 44100). Once the CD data has been ripped to your computer, that has no further bearing on anything you do with audio.

    As mentioned, all you need to worry about, is matching overall length & edits, and using a compatible samplerate.
    So, assuming you were wanting to reincorporate the CD Audio onto a new bluray, you would need an SR that is compatible with bluray. That means 48khz or 96khz. But basically 48. Running samplerate conversion on a 44.1khz source will NOT change duration (unless you are doing something wrong).
    If your final goal is just marrying bd video with cd audio for playback on general media players or computers, you really don't even need src.

    Scott
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  7. Converting from the CD sample rate of 44100Hz to a BD compatible sample rate of 48000 isn't a problem and I don't hear a difference at all.
    The problem here is the duration. I don't have a problem adjusting the audio between the songs where you only hear crowd noise. However the Audio runs out of synch even during the song so it just doesn't match. Adjusting in the middle of a song isn't a good idea.
    I tried to stretch it a bit in Adobe Audition but there is a loss in quality and it also didn't exactley match either.
    Since an Audio CD can't have a fps what would you guys describe as the closest fps similar to an Audio CD ? I would need that parameter as an input information for my EAC3to in order to make a conversion to the target fps of 24.
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  8. Member DB83's Avatar
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    One Q.

    Is that Audio CD an official recording or just an audience 'grab' ?

    Back in the day I was attempting something similar. Taking a pro-shot concert vid and attempting to match it with independent audio. It just will not sync.
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  9. Member Cornucopia's Avatar
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    @Gwar,

    Sound has a timebase measured in SAMPLES. Not counting the artificial packetization of certain compressed audio formats, which happens to use the term "frames" - and they do that only so that you know how it will fit in with groupings of video frames - there is only channels, samples per second, and bits per sample per channel. So 2ch + 16bit + 44100Hz is how you count Audio CD sound. Frames never figure into it. Nor should they.

    Look, if you've got video that is 24 frames/second and it has 24 frames, that amounts to 1 second worth. Or, each frame is 1/24th of a second.
    If you marry that with audio that ALSO is the same length of 1 second that happens to be sampled at 44100Hz, you will have 44100 samples. Which means that each frame will have 1837.5 samples of sound accompaniment.
    If that sound were the standard 48k samplerate, each 1 second would have 48000 samples. Which means that each frame from above would have 2000 samples. Much nicer to have an even number to deal with (which is one of the reasons why they chose 48kHz instead of 44.1kHz in the first place). But 1/2 a sample lead or lag - if you had to split the frames - would be totally unnoticeable, it amounts to 1/88200th of a second.

    No, the issue you are having deals not with "what framerate should it be" but with "how long in total duration should it be" or "when do they start the audio compared to the video" or "are the edits all identical in the audio compared to the video". And none of those should be affected by whichever samplerate you chose.

    Scott
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  10. @DB83
    it is an official released pro shot concert with an awful 5.1 mix with interview talking even over the actual concert footage. Together with this blu-ray comes a double audio cd which is therefore official as well but has a nice more powerful 2.0 mix and features the actual show without interruptions. So I want to completley use it as the Audio source for the footage. It sounds better and is more complete.

    @Cornucopia
    So one frame of video which equals one second can use 2000 samples of Audio information. But that calculation doesn't solve my problem. The Audio CD runs with a different speed than the Audio of the video footage. So if both Audio tracks start at the same time after about a minute the CD-Audio is out of synch with the video. It seems that that the compact disc audio is running slower.
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  11. Originally Posted by Gwar View Post
    So if both Audio tracks start at the same time after about a minute the CD-Audio is out of synch with the video. It seems that that the compact disc audio is running slower.
    Duration must be the same but the same duration not means that content is correlated - it can be altered framerate or something else - this is area i was concerned - at this moment you will be AUTHOR of the new mix.
    All i can advice is to use decent NLE with video and audio from BD source as reference and additional audio track from CD, then perform splice. trim and blend between CD and BD audio track to render new track with manually aligning CD vs BD audio in time domain.
    This is no longer conversion - this will be a new creation... not sure even if it is legal but not in a way that's i think is pursued on VideoHelp.
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  12. Member DB83's Avatar
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    I am still not sure that even a re-author can solve the OP's issues.

    I mentioned one scenario but I guess there are others.

    I am not that technical in this regard so this is an assumption on my part. The CD audio was recorded live through the venue's mixing deck hence the 'nice' mix that the OP refers to.

    The audio attached to the video did not go through the mixing deck but was sync recorded to allow for multi-camera edits at the post stage.

    So, essentially, there are two independent audio sources and never the twain would they meet.
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  13. Originally Posted by Gwar View Post
    It seems that that the compact disc audio is running slower.
    Get the two in sync at the start. Ie, you may need to add a delay or advance at the start. Then figure out how much longer the CD audio is. If EAC requires you to specify a frame rate just express that duration delta as a difference in frame rate. Say the audio is 4.27 percent longer and you need to specify it relative to 24 fps. Then speed it up to 24 * 1.0427 = 25.0248 fps.

    If the audio is then in sync at the start and end, but out of sync in the middle the problem is much more difficult because there are cuts and/or additions. In that case you'll have to locate those differences and adjust the audio accordingly.
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  14. no matter what you do you won't get a decent replacement of cd audio to the video..

    like what was said before cd went different editing process.. normally to fit cd playtime..
    also nobody likes dead space on cd audio so concert extras culled out..
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