[Mp4-tech] [Audio] Erroneous bit streams...

[sakthi narayanan]

  Hi,
  AAC Provides error handling in their codes.AAC bitstreams are arranges in form of syntactic elements.So,the corrupted bitstream will throw u the proper error in real time.For example,try to corrupt the frame length or some other field in the ADTS header.Try to decoded that corrupted bitstream using ur decoder.So,the decoder will give you the apporpriate error.
With Regards,
Sakthi Narayanan.D  
On Fri, 19 May 2024 Umang Garg wrote :
>Hello Guha,
>
>In broadcast environment you may encounter packet loss and stream corruption
>as two primary errors.
>
>For HEAAC:
>
>Stream corruption may be checked via CRC. ADTS format has a CRC check along
>with a separate CRC check for SBR decoding.
>
>Similarly, packet loss may also have to be handled gracefully within the
>decoder. In case of a loss of frame(s) the simplest technique is insertion
>of a silence frame (to maintain synchronization) but a more appropriate
>technique would be gradual muting.  As far as I know, the HEAAC standard
>does not say much about packet loss in general or the muting technique in
>particular. You may have to make your own decisions on that.
>
>Regards,
>Umang
>
>
>
>   _____
>
> From: mp4-tech-bounces lists.mpegif.org
>[mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of guhapriya ganapathy
>Sent: Thursday, May 18, 2024 5:19 PM
>To: mp4-tech lists.mpegif.org
>Subject: [Mp4-tech] [Audio] Erroneous bit streams...
>
>
>Dear all,
>
>Suppose you have an audio codec which is a part of a broadcast system (any
>system for that matter). What are the possible errors that might creep in
>the bitstream when it reaches the decoder? (There will be CRC check for each
>packet in the network layer, but I am concerned about the bitstream when it
>reaches the decoder.. what are the chances that the bit stream is
>corrupted?)
>Taking AAC HE as an example, Coding Technologies provides erroneous
>bitstreams for SBR (although SBR has CRC check) as a part of its
>certification package (wherein for example one bit in every third frame is
>corrupted - a random corruption!), whereas ISO does not(?) provide erroneous
>bitstreams. Of what value are erroneous bitstreams to the decoder? Is there
>a value add in generating erroneous bitstreams for decoders? If so, what is
>the approach so that it matches what happens in the real time?
>
>Regards,
>Guha Priya.
>
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