SV8 decoder lag

hrimfaxi · 25 April 2009, 06:06 am

Hi, I am working on a Sony PlayStation Portable(PSP) homebrew musepack player. Lately I switched to the SV8 libmpcdec(r435) to decoder SV8 files. But it seems to have some decode lag problem playing old SV7 file while the old SV7 library wouldn't. The lag occurs when PSP storage device light is flashing.

PSP storage device(Memory Stick) has a limited (or unstable) read speed, IMOO if the reading buffer is too large, it will cause this problem.

After investigation, I modified libmpcdec/internal.h to

Code:

#define DEMUX_BUFFER_SIZE (32768 - MAX_FRAME_SIZE) // need some space as sand box

as half of the previous one. And now, It seems to be OK.

But I wonder whether this hack will hurt the decoder? Or is there another better way to bypass this problem?

r2d · 25 April 2009, 03:26 pm

No, this should not hurt the decoder as long as the header blocks fit in the buffer (so MAX_FRAME_SIZE should even be enough). I don't see a better (easy) way right now.

25 April 2009, 06:06 am	#1
hrimfaxi Member Join Date: Feb 2008 Posts: 1	SV8 decoder lag Hi, I am working on a Sony PlayStation Portable(PSP) homebrew musepack player. Lately I switched to the SV8 libmpcdec(r435) to decoder SV8 files. But it seems to have some decode lag problem playing old SV7 file while the old SV7 library wouldn't. The lag occurs when PSP storage device light is flashing. PSP storage device(Memory Stick) has a limited (or unstable) read speed, IMOO if the reading buffer is too large, it will cause this problem. After investigation, I modified libmpcdec/internal.h to Code: #define DEMUX_BUFFER_SIZE (32768 - MAX_FRAME_SIZE) // need some space as sand box as half of the previous one. And now, It seems to be OK. But I wonder whether this hack will hurt the decoder? Or is there another better way to bypass this problem?

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25 April 2009, 03:26 pm	#2
r2d Musepack developer Join Date: Sep 2006 Location: Villeurbanne - France Posts: 36	No, this should not hurt the decoder as long as the header blocks fit in the buffer (so MAX_FRAME_SIZE should even be enough). I don't see a better (easy) way right now.