Audio Quality Loss (after one year...)

Myouh · Post by **Myouh** » Tue Oct 23, 2007 4:33 pm

after one year in the AMV creation world, I have just noticed that the difference between the quality of the original MP3 audio track and the quality of the final song on the AMV is quite big. I don't understand...
is it normal, this quality loss after converting from MP3 to Wave and later from Wave to the final format??
do all the AMVs have songs with a sound quality lower than the song on the original MP3 audio track?
(if not, how to avoid it?)

post-it · Post by **post-it** » Tue Oct 23, 2007 9:02 pm

Myouh wrote:..is it normal, this quality loss after converting from MP3 to Wave

yup! MP3's only hold a fraction of the Original Music when it is encoding the MP3.

Myouh wrote:and later from Wave to the final format??

hmm
.. lets say that the Original Audio was a song you liked off of that CD.
.. lets say that the MP3 Encode removed about 70% of the sound information.
now you want to re-create the Original Audio from the 30% leftover in the MP3.
.. lets say that your new MP3 looses 70% of that original 30% it started with.
What do we have left of the Original Audio ... 18% ??

.. these are just random numbers that I'm using here but they are trying to express why your MP3 can not become the Original Audio Again. MP3 is a Lossy Compression Format. Nothing Compressed can be totally UnCompressed -- its called a "lossy format" because a good portion of the information "will be lost."

Myouh wrote:.. do all the AMVs have songs with a sound quality lower than the song on the original MP3 audio track?
(if not, how to avoid it?)

Use the Audio recorded from your CD's Directly to your AMV -- no sound lost if every thing is Direct.

hope that helps a little in explaining your Compression issues

Myouh · Post by **Myouh** » Wed Oct 24, 2007 4:49 am

thanks for your explanations, but actually it is a MP3 to Wave convertion, then a Wave to MP3 convertion. it means I convert from MP3 (downloaded) to Wave to be able to wrok with it since Premiere doesn't accept MP3, and for the final compression I change PCM to MP3.
this process leads to a real quality loss that actually can't be noticed unless you listen to the two versions of the song one after one, which explains why I could 't notice the sound difference all this time...
I'm usually told that my videos have a good sound quality, but I started to doubt lately...

Myouh · Post by **Myouh** » Wed Oct 24, 2007 4:59 am

just to make things clearer...
I have a MP3 song. let's say its sound quality is 8/10.
convertion of the MP3 song to Wave. the Wave song sound quality is 8/10. (no quality loss)
entering of the Wave song to Premiere.
exportation of the video from premiere (video and sound uncompressed).
the PCM song on the video has a 6/10 sound quality. (loss of quality)
convertion from PCM to MP3. the final MP3 has a 6/10 sound quality. (no quality loss)
isn't it strange?

Scintilla · Post by **Scintilla** » Wed Oct 24, 2007 8:41 am

The MP3-to-PCM conversion can be ignored for purposes of estimating fidelity loss, because PCM is lossless (heck, it's uncompressed). Working with the example numbers you gave, the song takes that extra 20% hit when you convert from PCM back to MP3, not when you export uncompressed from Premiere.

It's not strange at all: your source was lossily compressed originally, and then you're lossily compressing it again. As Post-it said, if you want best results, your original source should be uncompressed (ripped off the CD or DVD to PCM WAV), so that it only has to get compressed once (when you compress the video for distribution).

Myouh · Post by **Myouh** » Wed Oct 24, 2007 10:12 am

hey Scintilla... I can't hide from you!
not even in the audio forum... haha

well, back to our subject... I'm sure of what I say.
the sound is already damaged on the uncompressed (PCM) version exported from premiere. it's damaged before the MP3 compression happens.
the loss of quality happens while the video gets out of premiere.
in my case, Wave to PCM = quality loss. I'm certain. this is what happens, and that's why I say it's strange... 'cause I completely understand what you said, and I agree that's what should happen, but somehow it's not like that with my audio files...

Scintilla · Post by **Scintilla** » Wed Oct 24, 2007 10:23 am

So the PCM version going into Premiere sounds better than the PCM version coming out of Premiere, you're saying. In that case, your audio export settings in Premiere may be at fault. Have you followed <a href="http://www.animemusicvideos.org/guides/ ... tml">these guidelines</a>?

Myouh · Post by **Myouh** » Wed Oct 24, 2007 10:50 am

New situation!
I've just noticed something even stranger...
I imported the MP3 song to premiere (I'm saying the unconverted MP3, the one with the good quality), and when I play it on premiere (before exportation, just on the timeline), it plays with a bad quality!!
it seems premiere reads all the audio files badly, no matter their format...
the problem comes directly from premiere's integrated player, not from the exportaton settings, since there's a quality loss even before exportation, at the timeline stage.
have you ever seen such a thing?

Scintilla · Post by **Scintilla** » Wed Oct 24, 2007 11:12 am

What are your project's audio settings?

Myouh · Post by **Myouh** » Wed Oct 24, 2007 11:35 am

Rate: 48000 Hz
Format: 16 Bit - Stereo
Compressor: Uncompressed
Interleave: 1 Second
(the rest is off)

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Audio Quality Loss (after one year...)

Audio Quality Loss (after one year...)

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