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Old 12th August 2013, 03:18   #1  |  Link
abdamon
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A question about using libaacplus encoder audio and checking it with vlc

I am learning HEAAC recently,and I make some try about it;Here is my problems:
I use libaacplus encode a audio,and check it with vlc;when I check the audio which is already encoded,the version of the audio is AAC+SBR V2;but when I check the audio that is encoding through the code stream,the version of the audio is AAC+SBR;
It is surprise that they are not the same!and i use logs to check what is different when the libaacplus encoding the audio.and the logs shows they are the same.
Could you help to tell me why they are different?thanks very much.
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Old 12th August 2013, 04:09   #2  |  Link
kieranrk
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Probably depends on bitrate and number of audio channels.
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Old 12th August 2013, 06:55   #3  |  Link
abdamon
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Quote:
Originally Posted by kieranrk View Post
Probably depends on bitrate and number of audio channels.
their bitrate are 32K.

before the bitrate judgement(if(nchannelsout==2 && bitrate<44001 && bitrate>16000)):
bitrate=32000,samplerate=48000,nchannelsout=2,useParamtricStereo=0;

after the bitrate judgement:
bitrate=32000,samplerate=48000,nchannelsout=1,useParamtricStereo=1;

during the process of two check ways,both audio channels and useParametricStereo are the same;
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Old 12th August 2013, 06:58   #4  |  Link
abdamon
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but all the samplerate turn to 24000 while encoding;
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Old 12th August 2013, 07:10   #5  |  Link
nevcairiel
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Quote:
Originally Posted by abdamon View Post
but all the samplerate turn to 24000 while encoding;
That would be SBR, it only codes half the sample rate and the SBR decoder can then restore the full sample rate.
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Old 12th August 2013, 07:20   #6  |  Link
abdamon
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Quote:
Originally Posted by nevcairiel View Post
That would be SBR, it only codes half the sample rate and the SBR decoder can then restore the full sample rate.
Thanks for you to help me.
But the parametric Stereo is irrelevant to SBR,All audio who's bitrate lower than 96K will be encoded with SBR;and those bitrate lower than 44k will plus Parametric Stereo.
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