[Ffmpeg-devel] [BUG] alignment problems: existing support in bitstream.h

[Christian Bienia]

Hi,

it looks like bitstream.h already supports aligned accesses, for
example:


#if defined(ARCH_SPARC) || defined(ARCH_ARMV4L) || defined(ARCH_MIPS)
#define UNALIGNED_STORES_ARE_BAD
#endif


and also:


#ifdef ALT_BITSTREAM_WRITER
static inline void put_bits(PutBitContext *s, int n, unsigned int value)
{
#    ifdef ALIGNED_BITSTREAM_WRITER
#        if defined(ARCH_X86) || defined(ARCH_X86_64)
    asm volatile(
[SNIP]
    );
#        else
[SNIP]
#        endif
#    else //ALIGNED_BITSTREAM_WRITER
#        if defined(ARCH_X86) || defined(ARCH_X86_64)
    asm volatile(
[SNIP]
    );
#        else
[SNIP]
#        endif
#    endif //!ALIGNED_BITSTREAM_WRITER
}
#endif


However, both ALT_BITSTREAM_WRITER and ALIGNED_BITSTREAM_WRITER are not
defined by default, and ffmpeg doesn't compile if they are defined. It
shouldn't be too hard to get alignment support to work again. Why was it
disabled?

- Chris