flac dev - Mar 2018 - Crash when writing 32bit flac files, am I doing something wrong ?

Hello,

I manage to successfully write 8, 16 and 24 bit, all stereo, FLAC files.
But when I try to write 32 bit FLACs my program crashes.

*FLAC__stream_encoder_set_bits_per_sample *is called to match the desired
bit depth (8, 16, 24, 32)

It's the same code for all bit depths, i provide a fixed-size signed int
buffer to the lib (size=16384), with values with appropriate ranges for
each bit depth (-128...+127 for 8 bit, etc.).

The crash happens in stream_encoder.c line 2263 :

*encoder->private_->integer_signal[channel][i] = buffer[k++];*

It happens when I call *FLAC__stream_encoder_process_interleaved**(encoder,
out, 16384/2)* in my code. Its working perfectly for all bit depth except
32 bit.


Output message: Unhandled exception at 0x00F98441 in fmcomposer.exe:
0xC0000005: Access violation writing location 0x00000000.


I'm using the latest code from the github repository. Reading the docs
didn't noticed any thing special to do for writing 32 bit FLACs, it seems
it should be supported. Maybe I am missing something ?



Regards

Stéphane
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On Thu, Mar 22, 2018 at 3:41 AM, Stéphane Damo <stephane.damo at
gmail.com> wrote:
> Hello,
>
> I manage to successfully write 8, 16 and 24 bit, all stereo, FLAC files.
But
> when I try to write 32 bit FLACs my program crashes.
>
> FLAC__stream_encoder_set_bits_per_sample is called to match the desired bit
> depth (8, 16, 24, 32)
>
> It's the same code for all bit depths, i provide a fixed-size signed
int
> buffer to the lib (size=16384), with values with appropriate ranges for
each
> bit depth (-128...+127 for 8 bit, etc.).
>
> The crash happens in stream_encoder.c line 2263 :
>
> encoder->private_->integer_signal[channel][i] = buffer[k++];
>
> It happens when I call FLAC__stream_encoder_process_interleaved(encoder,
> out, 16384/2) in my code. Its working perfectly for all bit depth except 32
> bit.
>
>
> Output message: Unhandled exception at 0x00F98441 in fmcomposer.exe:
> 0xC0000005: Access violation writing location 0x00000000.
>
>
> I'm using the latest code from the github repository. Reading the docs
> didn't noticed any thing special to do for writing 32 bit FLACs, it
seems it
> should be supported. Maybe I am missing something ?
AFAIK: while FLAC format itself supports 32-bit PCM, the official
encoder doesn't support it.

from include/FLAC/format.h:


/** The maximum sample resolution permitted by the format. */
#define FLAC__MAX_BITS_PER_SAMPLE (32u)

/** The maximum sample resolution permitted by libFLAC.
 *
 * \warning
 * FLAC__MAX_BITS_PER_SAMPLE is the limit of the FLAC format.  However,
 * the reference encoder/decoder is currently limited to 24 bits because
 * of prevalent 32-bit math, so make sure and use this value when
 * appropriate.
 */
#define FLAC__REFERENCE_CODEC_MAX_BITS_PER_SAMPLE (24u)

also, init_stream_internal_() function already checks bit depth:

    if(encoder->protected_->bits_per_sample <
FLAC__MIN_BITS_PER_SAMPLE || encoder->protected_->bits_per_sample >
FLAC__REFERENCE_CODEC_MAX_BITS_PER_SAMPLE)
        return FLAC__STREAM_ENCODER_INIT_STATUS_INVALID_BITS_PER_SAMPLE;


so, maybe you forgot to check return value for errors?

Yes, you're right I didnt check for much return error codes from libFLAC.
I'll do that and limit the bit depth to 24 bit in my program. Thanks for
your help !

On 24 March 2018 at 11:34, lvqcl <lvqcl.mail at gmail.com> wrote:
> On Thu, Mar 22, 2018 at 3:41 AM, Stéphane Damo <stephane.damo at
gmail.com>
> wrote:
> > Hello,
> >
> > I manage to successfully write 8, 16 and 24 bit, all stereo, FLAC
files.
> But
> > when I try to write 32 bit FLACs my program crashes.
> >
> > FLAC__stream_encoder_set_bits_per_sample is called to match the
desired
> bit
> > depth (8, 16, 24, 32)
> >
> > It's the same code for all bit depths, i provide a fixed-size
signed int
> > buffer to the lib (size=16384), with values with appropriate ranges
for
> each
> > bit depth (-128...+127 for 8 bit, etc.).
> >
> > The crash happens in stream_encoder.c line 2263 :
> >
> > encoder->private_->integer_signal[channel][i] = buffer[k++];
> >
> > It happens when I call
FLAC__stream_encoder_process_interleaved(encoder,
> > out, 16384/2) in my code. Its working perfectly for all bit depth
except
> 32
> > bit.
> >
> >
> > Output message: Unhandled exception at 0x00F98441 in fmcomposer.exe:
> > 0xC0000005: Access violation writing location 0x00000000.
> >
> >
> > I'm using the latest code from the github repository. Reading the
docs
> > didn't noticed any thing special to do for writing 32 bit FLACs,
it
> seems it
> > should be supported. Maybe I am missing something ?
>
> AFAIK: while FLAC format itself supports 32-bit PCM, the official
> encoder doesn't support it.
>
> from include/FLAC/format.h:
>
>
> /** The maximum sample resolution permitted by the format. */
> #define FLAC__MAX_BITS_PER_SAMPLE (32u)
>
> /** The maximum sample resolution permitted by libFLAC.
>  *
>  * \warning
>  * FLAC__MAX_BITS_PER_SAMPLE is the limit of the FLAC format.  However,
>  * the reference encoder/decoder is currently limited to 24 bits because
>  * of prevalent 32-bit math, so make sure and use this value when
>  * appropriate.
>  */
> #define FLAC__REFERENCE_CODEC_MAX_BITS_PER_SAMPLE (24u)
>
> also, init_stream_internal_() function already checks bit depth:
>
>     if(encoder->protected_->bits_per_sample <
> FLAC__MIN_BITS_PER_SAMPLE || encoder->protected_->bits_per_sample
>
> FLAC__REFERENCE_CODEC_MAX_BITS_PER_SAMPLE)
>         return FLAC__STREAM_ENCODER_INIT_STATUS_INVALID_BITS_PER_SAMPLE;
>
>
> so, maybe you forgot to check return value for errors?
> _______________________________________________
> flac-dev mailing list
> flac-dev at xiph.org
> http://lists.xiph.org/mailman/listinfo/flac-dev
>
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