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  1. Member
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    hello,

    converting a wmv file (i have a wmv quicktime thing installed) to DVD mpeg2enc for burning to dvd with toast 6.

    for some files i get a .m2v, .ac3, and a .wav file (i'm ignoring the .mpg file at the minute). e.g.:

    movie.wmv.ff.wav -- 70MB
    movie.wmv.ff.m2v -- 792MB
    movie.wmv.ff.ac3 -- 340k

    usually i just get a .m2v and .ac3 file (no .wav file), and the .ac3 file is of a reasonable size. when there's a .wav file as well, dropping the .m2v file into toast and burning as a dvd, the sound on the resulting dvd is noise for the first second or two, then silence throughout, which indicates toast is using the .ac3 file, whatever it contains when it's so small like in the above example, and not the .wav.... AH silly me, come to think of it i did get a warning from toast about not using the wav files because a valid Jam licence was not found (or something like that).

    number of questions:
    - if i had a Jam licence everything would be ok?
    - why do wav files sometimes appear and sometimes not? is it due to the particular contents/make up of the .wmv file in question?
    - if i hadn't of thrown away the .mpg file which ffmpegx makes (and instead thrown away the .wav, .m2v, .ac3 files, or just set ffmpegx to throw them away), and dropped the .mpg file into toast rather than the .m2v file, would all this not be an issue?, and finally,
    - if yes to the last question, is it possible to get ffmpegx to make the .mpg file from the .wav, .m2v, and ac3 files again without going through the long process of creating the .wav, .m2v, and ac3 files again first?

    thanks.
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  2. Explorer Case's Avatar
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    Originally Posted by jboyd
    - if i had a Jam licence everything would be ok?
    No, because the sound of this file doesn't seem to be converted correctly (final size too small, and as you said "noise + silence").

    Originally Posted by jboyd
    - why do wav files sometimes appear and sometimes not? is it due to the particular contents/make up of the .wmv file in question?
    Indeed. For some source files it needs a two step process: source > wav > ac3.

    Originally Posted by jboyd
    - if i hadn't of thrown away the .mpg file which ffmpegx makes (and instead thrown away the .wav, .m2v, .ac3 files, or just set ffmpegx to throw them away), and dropped the .mpg file into toast rather than the .m2v file, would all this not be an issue?
    That would work if the converted audio was okay.

    Originally Posted by jboyd
    - if yes to the last question, is it possible to get ffmpegx to make the .mpg file from the .wav, .m2v, and ac3 files again without going through the long process of creating the .wav, .m2v, and ac3 files again first?
    Toast re-multiplexes all input MPEGs anyway, so you might as well let it use the elementary streams (m2v + ac3).
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  3. Member
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    thanks very much for the reply.

    > Toast re-multiplexes all input MPEGs anyway, so you might as well let it use the elementary streams (m2v + ac3).

    but that's what i did/tried to do and it didn't work, hense this question. it resulted in a couple of seconds of noise then silence. definition of "that's what i did/tried to do": i dropped the m2v file into toast's video pane while the audio files (both the tiny ac3 and the wav files) were in the same folder as the m2v file, and let toast choose and do what it wanted with whichever audio files (which is when it said it won't do wav files).

    so unless i've misunderstood in some way it appears using the elementary streams (m2v + ac3) is not going to work, as that's what i've already tried to do (i think). the ac3 file is tiny so can't possibly have all the necessary info in it i don't think.

    it looks like to me at the moment, using the .mpg file is the only possible way to do it (if, as you say, the audio in that file is ok). if the mpg file is the only possible way, is there a way to make the .mpg file from the m2v, ac3, wav file without going through the process of making those elementary files again?

    thanks.
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  4. Explorer Case's Avatar
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    My guess is you've got about 22 mins of video, based on the size of your .m2v file. A corresponding .wav file then should be around 240 MB, not 70 MB. This .wav file is then used to create an .ac3 file. The .m2v and .ac3 files are then used to create the final .mpg file.
    The small size of the .wav file is indication to me that the audio conversion didn't go well. If something goes wrong in the first stage, then any manipulation with files from later stages won't fix it.

    Try opening the .wav file in QuickTime Player. Does it sound okay?
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    i see what you're saying. it's just under 28 mins long. the wav file does play ok in quicktime. i say ok, it does sound a bit crappy (slightly metalic) but i've just had a listen to the original and that's how it is, so yeah wav plays fine in quicktime.

    > This .wav file is then used to create an .ac3 file. The .m2v and .ac3 files are then used to create the final .mpg file.

    right so the fact the .ac3 file is clearly messed up (340k for 28mins) means that the audio on the mpg can't possibly be ok as it is made up from the ac3 file not the wav file. it does now look like to me if i did have a Jam licence toast would have done it ok -- it would have used the wav file successfully possibly.

    so ffmpegx is having a problem with the wav file. any suggestions? getting ffmpegx to make a good ac3 file is preferable to getting toast to deal with wav files.

    what qt says about the wav file:
    16-bit Integer (Little Endian), Mono, 22.050 kHz
    349.53 kbits/s

    it says mono but it doesn't just come out of one speaker; both.
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    Try separately transcoding the .wav file into ac3 using ffmpegx's audio-to-audio option. Ffmpegx will select some default settings; verify that they're what you want. Then, check the result, and then remux, reauthor.

    If that doesn't work for some reason, try transcoding from .wav into, say, aiff or another format using Audacity (free). Then take that result and use ffmpegx to convert to ac3.

    And as to sound coming out of both speakers, that can be mono (if both channels are identical). The number of speakers producing sound does not, by itself, tell you anything about whether it's stereo or mono.
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    > Try separately transcoding the .wav file into ac3 using ffmpegx's audio-to-audio option.

    ok i'll try that. thanks for the advice.

    > And as to sound coming out of both speakers, that can be mono (if both channels are identical). The number of speakers producing sound does not, by itself, tell you anything about whether it's stereo or mono.

    yup, i know that, just thought i'd mention that it wasn't coming out of only one speaker as i could imagine that possibly resulting in silence.. i don't know, but i know two speaker output doesn't mean stereo.

    ok, thanks.
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  8. Explorer Case's Avatar
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    Originally Posted by tomlee59
    Ffmpegx will select some default settings; verify that they're what you want.
    About the audio settings: make sure your .ac3 is sampled at 48 kHz per DVD specs; keep it mono as your source is that too; you won't need the 448 kbps bitrate as that is aimed at 5.1 channels. (Screenshot)
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    > About the audio settings: make sure your .ac3....

    got ya, will try that later, excellent, thanks.
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    yup, this has basically worked, except the audio is out of sync with the video: the audio about 3 to 4 seconds too early.

    is it possible with ffmpegx to add a certain amount of time (empty sound) to the start of the audio?

    thanks.
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  11. Explorer Case's Avatar
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    Yes, with a Sync value (in milliseconds).
    Either in the Options tab for new encodes,
    or in the Tools > Mux tab for just muxing video and audio.
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    Just fyi: In the muxing tool, a positive number delays the video. In your case, the audio needs to be delayed, so you will enter a negative number.

    VLC is very useful for determining the right value (cuts down on the number of iterations you have to try). Under Preferences, VLC allows you to dial in a sync offset. Of course, Murphy says that the sign convention for VLC is the precise opposite of that in ffmpegx tools -- a positive number delays the audio. Once you've got a value dialed in that gives you good sync throughout, plug in the same value into ffmpegx (but with the opposite algebraic sign) and you'll be good to go.
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    ok, haven't tried this yet but will do. thanks v. much for the info/replies.
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