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Rockbox mail archiveSubject: Re: MPEG Audio formatRe: MPEG Audio format
From: Bluechip <csbluechip_at_gmail.com>
Date: Sat, 14 Jan 2006 06:05:00 +0000 At 04:39 14/01/2006, you wrote: >I just ran lame with no options on the first file I found and got the >following output: >--------------- >LAME version 3.96.1 (http://lame.sourceforge.net/) >CPU features: MMX (ASM used), SSE, SSE2 >Using polyphase lowpass filter, transition band: 17249 Hz - 17782 Hz >Encoding concat.wav to concat.mp3 >Encoding as 44.1 kHz 128 kbps j-stereo MPEG-1 Layer III (11x) qval=3 > Frame | CPU time/estim | REAL time/estim | play/CPU | ETA > 2379/2381 (100%)| 0:09/ 0:09| 0:10/ 0:10| 6.2245x| 0:00 >average: 128.0 kbps LR: 849 (35.64%) MS: 1533 (64.36%) > >Writing LAME Tag...done >ReplayGain: -0.8dB >----------------- >As you can see on the line starting with "average" this particular sample >used joint-stereo on 64% of the frames. > >If you don't have lame installed or can't find a track that produces both >kind of frames, I can easily put this file somewhere. LR: 849 (35.64%) MS: 1533 (64.36%) Means that 64.36% of the Joint Stereo frames utilise the "+MS" thing ...I have no idea what it is, but I do know it is a Joint Stereo enhancement held in the MODE bits of the header - which are only relevant if the CHANNEL bits are set to Joint Stereo. There is also a "+IS" (intentsity stereo) and the combo "+M/S +IS" BC >David > > > > > >When it comes to sample rate, layer and version switching, I think you're > > >reasonably safe, though it is probably legal. Stereo mode I think you >will > > >find encoders may switch from frame to frame. > > > > Is anyone in a position to send me an example file please? Or seond-best, > > name an encoder with a required set of options. > > > > Difficult to test my app without test data - and quite a chore to > > manufacture such a file by hand. (...and that bit of the app is not yet > > written) > > > > BC > > > > Received on 2006-01-14 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |