Which type of WAV should I choose when decoding an MP3?

[mob]

Hey guys,

I will be using BeSweet to convert a PAL MP3 to an NTSC WAV.

I normally use LAME to decode MP3's but since I need to change the framerate I will have to use BeSweet as I don't think this can be done with LAME.

When I'm done I will take that WAV file and encode it back to MP3 using LAME command line version. I know BeSweet can do the job by simply going from PAL MP3 to NTSC MP3 (skipping the whole decoding to WAV process). But since BeSweet is so old, it doesn't work too well with the new version of LAME that I need to use (as I've learned from a previous thread I posted here).

Well anyway, I see that BeSweet has the following options when decoding the MP3 to WAV:

http://img294.imageshack.us/img294/852/34563vv5.jpg

But which one am I supposed to select?

P.S.: Is there any other software that can convert PAL MP3 straight to NTSC MP3 and allow me to skip the whole decoding to WAV process? Or should I just stick with BeSweet?

[nautilus7]

I can't help you with besweet, but i can suggest an alternative method. Use eac3to. Decode to wav with lame, use eac3to to do the pal2ntsc conversion (the pitch will be changed) and then encode with lame.

eac3to command line: eac3to input.wav output.wav -slowdown

[mob]

Cool! I'll definitely have to check out eac3to!

Up until now I always thought BeSweet was the only thing that can do the PAL to NTSC conversion.

Thanks for letting me know about it. I hope it will work beautifully :)

[tebasuna51]

Mp3 (lame) only suport stereo audio then obviously you need select: 16 bit stereo wave

Please use BeLight (GUI for BeSweet) updated to offer more quality conversions or BeHappy.

You can see also this thread (http://forum.doom9.org/showthread.php?p=1126217#post1126217)

[mob]

Oh man, BeHappy is good :)

So I tried eac3to like was suggested. And it works also. But I have to wait a much longer time because I have to go from PAL MP3 to PAL WAV to NTSC WAV to NTSC MP3.

But with BeHappy I simply go from PAL MP3 to NTSC MP3. Directly. And it is very fast.

There is only one thing I find strange and maybe you guys will know why:

If I take a 25fps Video that has the length of 0:21:00.840 and I change it to 23.976fps then I get a video of 0:21:54.678. So far so good.

But then when I transcode the audio and make it to 23.976fps it goes from 0:21:00.840 to 0:21:54.696.

So how come it gets longer than the video by a few milliseconds? Should it now get the same length as the video also? Maybe it's not so accurate like Vdub?

[tebasuna51]

There is only one thing I find strange and maybe you guys will know why:

If I take a 25fps Video that has the length of 0:21:00.840 and I change it to 23.976fps then I get a video of 0:21:54.678. So far so good.

But then when I transcode the audio and make it to 23.976fps it goes from 0:21:00.840 to 0:21:54.696.

So how come it gets longer than the video by a few milliseconds? Should it now get the same length as the video also? Maybe it's not so accurate like Vdub?

A 25 fps video of 21:00.840 have exactly 31521 frames (each frame 40 ms), played at 24000/1001 frames by second the duration is 21:54.688.

A mp3 have also frames (minimal length to encode) of 24 ms. If we use 54778 frames the duration is 21:54.672, not enough, we need 54779 frames (21:54.696), the end of last frame is filled with silence.

Don't worry with a few ms.

[mob]

Thanks tebasuna51!

So 24000/1001 is exactly 23.976023976023976023976023976024 but and you say it should give out 21:54.688 for my video. But yeah since Vdub doesn't let me put 23.976023976023976023976023976024 so I have to put 23.976 and I get 21:54.678 in the end.

But this is not a problem with my conversion, just a problem with Vdub then. So thanks for clearing that one up for me because now I understand it a lot more :)

Anyway like you said, only a few ms is nothing to worry about, and I guess it is normal to have that difference anyway.

It's good that you know so much about it. Thanks for explaining it to me.