[FFmpeg-devel] Issue with ffmpeg mp3 decoder on ARM11

[Alexy]

Hello All,

 The problem is fixed, it was an issue with the tool chain.  The tool chain
i was using to build ffmpeg was 3.3.2, while the target file system had
libraries built with 3.4.4. I built ffmpeg with gcc 3.4.4 and that worked.

Thank you for the suggestions and pointers, you guys saved my day.

Alexy

On 7/18/07, Alexy <galahad at gmail.com> wrote:
>
> Hello,
>
>  Thank you for the explanatory mail.
>
> > Normally A32_BITSTREAM_READER is used on ARM. If you enforced some
> > nonstandard configuration, also beware of various possible bugs which
> > may be
> > caused by it. For example, many ARM devices require strict alignment and
> > unaligned memory accesses will cause various bugs (the result of memory
> > read/write operation may differ from what you expect). Though ARM11
> > supports
> > unaligned memory access in hardware, it may be disabled. At least it is
> > disabled on Nokia N800 (which uses OMAP2420) in current version of its
> > firmware. So be sure to check all the configure options or just try a
> > standard
> > default configuration first.
>
>
>  I doubted this too, the output buffer memory that i am giving is aligned
> to 32 bytes just to be sure. I have tried with arm4l configuration, but even
> with that there is no change in the output (its still all zeroes). If i
> disable optimizations while configuring ffmpeg (with --disable-opts), the
> output has 0xffff thrown in once in a while in between a chunk of zeroes.
>
> ARM11 may have hardware floating point support. Try to check /proc/cpuinfo
> > on your device as M?ns suggested, if it lists 'vfp', you have hardware
> > floating point supported. I suspect that the possibility of your
> > OMAP2430
> > (I guess it from some paths in your compiler output) having hardware
> > floating point supported is very high.
>
>
>  You are right, the ARM11 that i use does support hardware floating point,
> it was my mistake. Sorry. But i dont think the libm that i use supports it
> (i read on sourceforgery that they do not plan to support hardware fp's in
> their libm's) the /proc/cpuinfo is given below. And yes, i am using
> OMAP2430.
>
>
> > Though ffmp3 is a fixed point decoder, it contains a bit of floating
> > point
> > math in performance non-critical parts of code (mostly initialization).
> > If
> > floating point support is broken in your compiler, it may have caused
> > the
> > bugs you are seeing. You can try to compile a few simple test programs
> > using floating point math to check if your compiler generates binaries
> > that
> > can be executed and work properly on your device. If some simple
> > examples break, you should try to fix that first before doing further
> > experiments with ffmpeg.
>
>
>  I will try these. Thank  you.
>
>
> By the way, you may want to also check libmad as alternative fixed point
> > mp3
> > decoder, it is even a bit faster than ffmp3 on ARM right now.
>
>
> Ok, i will check this out too.
>
>
> Thank you for all the help guys..
>
> Regards,
>
> Alexy
>
> 1) my /proc/cpuinfo
>
> Processor       : TI OMAP2430 (ARM1136JF-S) rev 5 (v6l)
> BogoMIPS        : 219.54
> Features        : swp half thumb fastmult vfp edsp java
> CPU implementer : 0x41
> CPU architecture: 6TEJ
> CPU variant     : 0x0
> CPU part        : 0xb36
> CPU revision    : 5
> Cache type      : write-back
> Cache clean     : cp15 c7 ops
> Cache lockdown  : format C
> Cache format    : Harvard
> I size          : 32768
> I assoc         : 4
> I line length   : 32
> I sets          : 256
> D size          : 32768
> D assoc         : 4
> D line length   : 32
> D sets          : 256
>
> Hardware        : OMAP24xx 2430SDP
> Revision        : 24300124
> Serial          : 0000000000000000
>
>
>