[FFmpeg-devel] [PATCH v15 1/2] lavc/svt_hevc: add libsvt hevc encoder wrapper

[Limin Wang]

On Tue, Jul 30, 2019 at 07:48:43PM +0200, Carl Eugen Hoyos wrote:
> Am Di., 30. Juli 2019 um 15:20 Uhr schrieb James Almer <jamrial at gmail.com>:
> >
> > On 7/30/2019 2:59 AM, Limin Wang wrote:
> > >> +    if (avctx->flags & AV_CODEC_FLAG_GLOBAL_HEADER) {
> > >> +        EB_BUFFERHEADERTYPE *header_ptr = NULL;
> > >> +
> > >> +        svt_ret = EbH265EncStreamHeader(svt_enc->svt_handle, &header_ptr);
> > >> +        if (svt_ret != EB_ErrorNone) {
> > >> +            av_log(avctx, AV_LOG_ERROR, "Failed to build stream header\n");
> > >> +            goto failed_init_encoder;
> > >> +        }
> > >> +
> > >> +        avctx->extradata_size = header_ptr->nFilledLen;
> > >> +        avctx->extradata = av_malloc(avctx->extradata_size + AV_INPUT_BUFFER_PADDING_SIZE);
> > > It's preferalbe to use av_mallocz
> >
> > He was asked to do it this way as it's faster. No need to zero the whole
> > buffer if it's going to be written to immediately afterwards. Only the
> > trailing padding bytes needs to be zeroed.
> 
> In this case I suspect there is an unneeded cast in the next line.

FYI:
libavcodec/avcodec.h comments for the extradata_size
      * The allocated memory should be AV_INPUT_BUFFER_PADDING_SIZE bytes larger
      * than extradata_size to avoid problems if it is read with the bitstream reader.
      * The bytewise contents of extradata must not depend on the architecture or CPU endianness.
      * Must be allocated with the av_malloc() family of functions.


> 
> Carl Eugen
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