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aliumalik
29th June 2004, 09:09
Hi,
I just wanted to know that if I have two files, file1 being 128kbit/s and file2 is just a conversion of file1 to 320kbit/s. Both are mp3s. Is there any way by which I can tell that the 320kbit/s file's acutal bitrate is 128kbit/s.
Thanks

/\o/\
29th June 2004, 09:23
i think quality reduces or is the same as 128

jkwarras
29th June 2004, 09:54
Originally posted by aliumalik
Is there any way by which I can tell that the 320kbit/s file's acutal bitrate is 128kbit/s.

Sorry, but I don't understand what you mean. Can you explain better please?

If what you want is 'mark' the 320 kbps file as a re-encode from a 128 kbps mp3, just tag 'comment' as 're-encoded from a 128 kbps mp3' :cool:

If what you want is to know what's the real bitrate of he encoded file you may want to use something like 'encspot' (google is your friend).

aliumalik
29th June 2004, 11:53
What I meant was that I rip a track off a cd to a 128k mp3 file and then I re-encode that mp3 file from 128K to 320K. The quality of the 2 will obviously be the same but is there any way I can tell from the 320k file that its bitrate is actually 128.

EDIT Is there some software like encspot for other formats like aac and vorbis?

Slogra
29th June 2004, 12:22
The 320kbps mp3 will be even worse than the 128kbps mp3, as transcoding will always give you worse quality.

Anyway, there is no easy way of telling an mp3 is transcoded. The only real way is to listen very carefully and compare it to the original CD.

128kbps have a lowpass of about 16khz, so any frequencies higher than that are lost forever. So the 320kbps mp3 doesn't have these high frequencies either.

So what might help is looking at the spectrum graph, that most (advanced) wav editors can display. If you see a cap at 16khz then it'll probably transcoded from a 128kbps.

Now the problem with this method is that:

1) the original CD source might not have frequencies above 16khz. Probably older CDs or just badly mastered CDs.
2) you can disable the 16khz lowpass when encoding 128kbps, this will result in horrible overal sounding mp3, but in the frequency graph you will still show the high frequencies. So the graph doesn't say anything in this case.

jkwarras
29th June 2004, 12:28
Originally posted by aliumalik
is there any way I can tell from the 320k file that its bitrate is actually 128.

No. The 'new' re-encoded file is a new file in itself. if you don't tag the file with something telling you where does it comes from, there's no way (apart of trying whit slogran suggest :rolleyes:) to know it.

Is there some software like encspot for other formats like aac and vorbis?

Try foobar2000, is an audio player but support almost any audio format and return a lot of technical info about any file (under properties). I think there's another one named 'Mr questionman' a sort of encspot evolution. Check Hydrogenaudio.org forums :cool: