Support and General Use > Audio Playback, Database and Playlists
Codec Efficiency Comparison Test (iPod)
soap:
--- Quote from: bk on October 08, 2006, 01:05:53 PM ---
--- Quote from: Davide-NYC on October 08, 2006, 12:38:33 PM ---Hmm. Agreed, I'll modify the batch file to encode in CBR in all possible instances.
--- End quote ---
Forcing CBR for natively VBR formats (Ogg Vorbis) would be misleading. I think the value of these benchmarks is not necessarily in the comparison but rather in the absolute boost level per target. In other words it's less useful to compare codec A to codec B, but more useful to know that codec A is 20% slower on ARM relative to ColdFire.
--- End quote ---
Forcing at least ABR is a must for this test to mean anything. Comparing MP3 to OGG when the bitrates differ substantially is worthless.
As for the original encodings, only 192 and 256 are useful, IMHO.
senab:
Yes this test wasn't really a test on bitrates against each other and you couldn't really do such a test. Bitrates will change on the individual sample, (ie Vorbis q6 is supposedly ~192, but gives me ~180 very often).
What you can do with the results is plot a bitrate vs boost ratio scatter graph and then create a line of best fit to compare how the bitrates between teh codec's.
soap:
--- Quote from: senab on October 08, 2006, 04:39:07 PM ---Yes this test wasn't really a test on bitrates against each other and you couldn't really do such a test. Bitrates will change on the individual sample, (ie Vorbis q6 is supposedly ~192, but gives me ~180 very often).
What you can do with the results is plot a bitrate vs boost ratio scatter graph and then create a line of best fit to compare how the bitrates between teh codec's.
--- End quote ---
Why couldn't you force ABR or CBR on the codecs that support it? Even if the different codecs allocate bits inconsistently throughout the song, the test is the average boost percentage for the song is it not? So as long as the average bitrates are comparable the test should provide a valid comparison.
senab:
Well thats it, would using CBR put less of a strain on the CPU? It would be an unfair test then. Here's the type of graph I was thinking of:
soap:
Maybe CBR would present less of a strain, but I believe most/all support ABR.
Regardless, your graph has won me over.
EDIT:
(as long as the X-axis is the actually achieved ABR, not the attempted BR)
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