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Algorithm delay calculation for AAC LC for a 16khz stream?, Algorithm delay of aac lc encoder and decoder
satish babu
post Feb 8 2013, 15:44
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Hi Techies,

I want to measure the quality of my AAC-LC encoder for a particular stream @16khz sampling frequency.
I had Encoded and decoded the stream with bitrate@32kbps,mono channel.

As per my understanding,algorithm delay for a 48khz stream is 1024(1 frame delay by encoder)+512(half of that by decoder).I have a tool which can measure the quality of encoder for 44.1/48 khz stream.
But, as i want to measure the quality of my encoder @16khz sampling fr,i had downsampled an 48khz stream to 16khz stream(using goldwave tool) and after processing(encoder+decoder) again i had upsampled the output to 48khz stream.
I need to mention the algorithm delay(in terms of samples) to my quality measurement tool,but i am struck with calculation of algorithm delay in this scenario.

Please throw some light on this issue...


Thanks In Advance,
satish
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saratoga
post Feb 8 2013, 20:43
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Just manually time align the two samples in an audio editor.
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satish babu
post Feb 11 2013, 07:01
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QUOTE (saratoga @ Feb 8 2013, 13:43) *
Just manually time align the two samples in an audio editor.


I want to know the actual logic to calculate the delay introduced by encoder for an 16Khz input.

Thanks & Regards,
satish
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C.R.Helmrich
post Feb 11 2013, 11:50
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Search for the paper "A guideline to audio codec delay" by Manfred Lutzky et al. Was presented at an AES conference, I think, and might be available for free.

Chris


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satish babu
post Feb 15 2013, 08:08
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QUOTE (C.R.Helmrich @ Feb 11 2013, 04:50) *
Search for the paper "A guideline to audio codec delay" by Manfred Lutzky et al. Was presented at an AES conference, I think, and might be available for free.

Chris


Hi Chris,

Thank you for your reply.

Actually, already i had gone through that paper,but i didn't get any calculation for an 16khz sampling frequency input stream. AAC-LC delay calculations in that paper were w.r.t 48khz sampling fr stream.
Can you please let me know what extra factor will come into picture when the input stream is @16khz sampling fr?

Thanks & Regards,
satish
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