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  1. I have a divx file with mp3 audio at 127 kbps. Would this mean converting to vcd i shud just use a audio bitrate of 127? I read somewhere that mp3 bitrate is equal to a little bit more for mpeg1 vcd audio. Like 128 = 160 or somethin. Any ideas? I dont want to waste space, but keep my quality as good as the source.
    PlaiBoi
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  2. No, you should use the standard audio bitrate.

    Regards.
    Michael Tam
    w: Morsels of Evidence
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  3. Member
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    If you're converting to VCD, the standard specifies 224k audio. Anything else and it's nonstandard (XVCD). If you're OK with making XVCD, or if you're making SVCD (which allows different audio bitrates), you'll definitely need a higher MP2 bitrate to get the same quality as the MP3. A 128k MP3 probably needs a 160k or 192k MP2 for comparably quality.

    There aren't any hard-set rules, and quality is subjective anyway. But you're really not saving much space by using a lower bitrate.
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  4. no, vitualis, im not going to use the standard bitrate. I kno im makin an xvcd.

    thanx sterno for the info. btw, i will be wasting space, wether its a little or alot, its still wasting space. Why use 224 when 192 is the max quality? I can use the remaining space for higher video bitrate.
    PlaiBoi
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  5. You are going to cause a generational loss of quality with re-encoding the audio. You cannot simply say that because the original audio was (for example, 128 kbit/s), that re-encoding it to any particular figure will "keep the quality".

    Consider the following:
    If I have an MPEG video clip encoded at 800 kbit/s (i.e., relatively low quality), will re-encoding it at 800 kbit/s "maintain the quality"? The answer is far from it. You will incur a generational loss of quality and the relatively low bitrate you are now encoding to will make it all that little bit worse.

    Back to the audio. MP2 is relatively less efficient that MP3 at lower bitrates. Thus a 128 kbit/s MP3 clip is comparable to probably 160-192 kbit/s MP2 when encoded from original source.

    This means that you will not "maintain" the quality when re-encoding it to 192 kbit/s MP2. Rather, it means that re-encoding it to 192 kbit/s MP2 will probably sound about the same if you re-encode the MP3 to 128 kbit/s MP3.

    Now, it is widely accepted that 224 kbit/s MP2 audio is near transparency which means that you can't really tell the difference from the original. This means, if you want to make your already compressed audio from deteriorating much more, then you should use 224 kbit/s.

    However, if you are willing to accept a loss of audio quality, then by all means use whatever audio bitrate you feel is best.

    Regards.
    Michael Tam
    w: Morsels of Evidence
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