On Sat, 6 May 2017, Ronald S. Bultje wrote:
Hi,
On Sat, May 6, 2017 at 5:20 AM, Nicolas George <geo...@nsup.org> wrote:
+ /**
+ * Minimum alignment of frame data required by the codec.
+ * All frame data pointers must have the alignment lower bits cleared,
+ * i.e. be a multiple of 1<<alignment.
+ * - encoding: set by the encoder and used by the framework
+ * - decoding: unused
+ */
+ unsigned alignment;
+
} AVCodecContext;
I agree it's likely that one codec (e.g. h264) would need 32-byte alignment
on a particular system (e.g. x86/haswell), whereas another codec on the
same system (e.g. wmavoice) might not.
However, I find it unlikely that one codec *instance* would need different
alignment from another codec *instance* (for the same codec).
I can imagine a case where alignment requirements are dependant on pixel
format. Not the best example, because it is not a "codec", and it is using
bitpacked formats, but the Decklink output device would require 128 byte
or even 256 byte alignment for 10/12 bit, according to the SDK.
Regards,
Marton
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