[Speex-dev] Decoding only a certain frame results in different values than when decoding the entire file

Hermann Weber hermie.weber at gmx.de
Fri Dec 23 10:54:52 PST 2011

And how many frames does Speex need to "recover"?
Or is that not predictable?


Am 23.12.2011 19:17, schrieb Steve Checkoway:
> On Dec 23, 2011, at 10:03 , Hermann Weber wrote:
>> I found out something:
>> The more frames I decode before the frame that I actually want to
>> decode, the better the quality becomes.
>> For example when I basically want to decode frame #100, I read frame #80
>> to #100, and then frame 100 has the quality that I need.
>> Why? Is there any information on this behaviour?
> Speex is a stateful encoder. As it encodes the audio, the state 
> changes. As it decodes, the state changes. You're trying to start 
> somewhere in the middle with the initial state rather than with the 
> state it would have if you started from the beginning and decoded it 
> all. As you've noticed, it can recover from lost frames over time.
> This is just repeating what Lakhdar Bourokba already said though.
> As for your question about the header, it really depends on how you're 
> saving the encoded file.
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