[opus] Initial implementation of ch.mapping 253/3

Wed Jun 7 15:02:06 UTC 2017

Thanks for looking over this, Mark! I'm travelling this week but when I'm
back I'll address all of your concerns and send,out another patch. :)

On Jun 7, 2017 9:56 AM, "Mark Harris" <mark.hsj at gmail.com> wrote:

> On Tue, May 30, 2017 at 3:13 PM, Drew Allen <bitllama at google.com> wrote:
> > Hello all,
> >
> > Attached is the initial proposed implementation for ch.mapping 253/3,
> based
> > on the IETF proposal:
> > https://tools.ietf.org/html/draft-ietf-codec-ambisonics-03
> >
> > A brief overview of the patch, as it is slightly lengthy:
> > After discussion with Jean-Marc, we determined that ch.253/3 will need
> the
> > demixing matrix as part of the encoder/decoder struct stack and thus will
> > require a new Encoder/Decoder structure. For this, I've proposed
> > OpusPEnc/OpusPDec (for "projection"), which wraps OpusMSEnc/OpusMSDec
> aside
> > from the addition of the mixing matrix structure. The functionality also
> > wraps the functionality of the multistream API aside from matrix
> transforms
> > during encode/decode.
> >
> > We have included 3 mixing/demixing matrix pairs that are sufficient for
> > coding/decoding 1st/2nd/3rd order content respecitvely.
> >
> > I've modified the multistream api slightly, first to include some
> > supplemental API extensions to allow wrapping and moved the declaration
> of
> > the MSEnc/MSDec to opus_private so that the projection API can compile.
> >
> > Some basic tests to ensure matrix multiplication and encoding/decoding
> using
> > projection has been included.
> >
> > I am of course happy and eager to take any and all
> > suggestions/comments/questions/recommendations regarding the patch,
> > including naming conventions/style/etc.
> >
> > Looking forward to your feedback,
> >
> > Cheers,
> > Drew
>
>
> Hi Drew,
>
> I ran into some issues with this new test.
>
> Building the test for floating point produces a clang compiler warning:
>
>   CC       tests/test_opus_projection.o
> tests/test_opus_projection.c:137:9: warning: using floating point
> absolute value function
>       'fabs' when argument is of integer type [-Wabsolute-value]
>     if (ABS16(a[i] - b[i]) > tolerance)
>         ^
> ./celt/arch.h:194:26: note: expanded from macro 'ABS16'
> #define ABS16(x) ((float)fabs(x))
>                          ^
> tests/test_opus_projection.c:137:9: note: use function 'abs' instead
> ./celt/arch.h:194:26: note: expanded from macro 'ABS16'
> #define ABS16(x) ((float)fabs(x))
>                          ^
>
> Also the test fails to compile with -std=c89:
>
> tests/test_opus_projection.c:57:1: error: C++ style comments are not
> allowed in ISO C90
>  // static const MappingMatrix test_matrix = {
>  ^
> tests/test_opus_projection.c:57:1: error: (this will be reported only
> once per input file)
> tests/test_opus_projection.c: In function 'main':
> tests/test_opus_projection.c:403:1: warning: control reaches end of
> non-void function [-Wreturn-type]
>  }
>  ^
>
> Running the test, an issue occurs in test_creation_arguments().
> opus_projection_ambisonics_encoder_create() is intentionally called
> with invalid arguments (initially, channels=0), which causes an error
> to be returned and streams and coupled_streams are left uninitialized.
> These uninitialized values are passed to
> opus_projection_decoder_create(), which does not check that the
> arguments are not too large before using them to attempt allocation of
> a ridiculous amount of memory.  Results may vary depending on the
> uninitialized values of streams and coupled_streams.  Valgrind reports
> several uses of uninitialized values such as:
>
>  Conditional jump or move depends on uninitialised value(s)
>     at 0x100067B72: opus_multistream_decoder_get_size
> (opus_multistream_decoder.c:47)
>     by 0x10006B098: opus_projection_decoder_get_size
> (opus_projection_decoder.c:54)
>     by 0x10006B136: opus_projection_decoder_create
> (opus_projection_decoder.c:68)
>     by 0x10000140D: test_creation_arguments (test_opus_projection.c:273)
>     by 0x100001D06: main (test_opus_projection.c:396)
>   Uninitialised value was created by a stack allocation
>     at 0x100001330: test_creation_arguments (test_opus_projection.c:252)
>
> Additionally, the demixing_matrix appears to be used uninitialized
> when order_plus_one is 1 (or greater than 4):
>
>  Conditional jump or move depends on uninitialised value(s)
>     at 0x10006A6DF: opus_projection_encoder_init_impl
> (opus_projection_encoder.c:125)
>     by 0x10006A9CA: opus_projection_ambisonics_encoder_init
> (opus_projection_encoder.c:196)
>     by 0x10006AC7B: opus_projection_ambisonics_encoder_create
> (opus_projection_encoder.c:261)
>     by 0x1000013D9: test_creation_arguments (test_opus_projection.c:268)
>     by 0x100001D06: main (test_opus_projection.c:396)
>   Uninitialised value was created by a heap allocation
>     at 0x10010FE71: malloc (vg_replace_malloc.c:302)
>     by 0x10006AB84: opus_alloc (os_support.h:49)
>     by 0x10006AC1F: opus_projection_ambisonics_encoder_create
> (opus_projection_encoder.c:252)
>     by 0x1000013D9: test_creation_arguments (test_opus_projection.c:268)
>     by 0x100001D06: main (test_opus_projection.c:396)
>
> Another issue occurs in mapping_matrix_dot_short().  It attempts to
> read beyond the end of the input buffer and may cause a segmentation
> fault.  It appears that the input buffer contains only 2 channels of
> 480 samples each, but 16 channels of 960 samples each are being read
> from the buffer.  Valgrind reports the following:
>
>  Invalid read of size 2
>     at 0x10006B9D8: mapping_matrix_dot_short (mapping_matrix.c:98)
>     by 0x10006BABD: mapping_matrix_multiply_short (mapping_matrix.c:119)
>     by 0x10006AD5B: opus_projection_encode (opus_projection_encoder.c:283)
>     by 0x100001BCB: test_encode_decode (test_opus_projection.c:374)
>     by 0x100001D2D: main (test_opus_projection.c:400)
>   Address 0x10490b000 is not stack'd, malloc'd or (recently) free'd
>
>  Process terminating with default action of signal 11 (SIGSEGV)
>   Access not within mapped region at address 0x10490B000
>     at 0x10006B9D8: mapping_matrix_dot_short (mapping_matrix.c:98)
>     by 0x10006BABD: mapping_matrix_multiply_short (mapping_matrix.c:119)
>     by 0x10006AD5B: opus_projection_encode (opus_projection_encoder.c:283)
>     by 0x100001BCB: test_encode_decode (test_opus_projection.c:374)
>     by 0x100001D2D: main (test_opus_projection.c:400)
>
>  - Mark
>
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