Re: [FFmpeg-devel] [PATCH] avformat/avcodec: Add DTS-UHD demuxer and parser, movenc support.

[Paul B Mahol <onemda@gmail.com>]

On Wed, Jun 14, 2023 at 2:00 AM Roy Funderburk <royffmpeg@funderburk.us>
wrote:

>
> On 6/13/23 11:35 AM, Paul B Mahol wrote:
> > Doing allocation in probe?
> > Probing should be very fast.
>
> In line 143 of the avformat patch, memory allocation is removed from the
> probe
>
> >>+int dtsuhd_frame(DTSUHD *h, const uint8_t *data, size_t data_bytes,
> >>+                DTSUHDFrameInfo *fi, DTSUHDDescriptorInfo *di)
> >>+{
> >>+    gb = &h->gb;
> >>+    init_get_bits(gb, data, data_bytes * 8);
> > init_get_bits8, and check return code.
>
> In line 986 of the avcodec patch, changed to using init_get_bits8 and
> added return code check.
>
> >>+        fi->sync = h->is_sync_frame;
> >>+        fi->frame_bytes = h->frame_bytes;
> >>+        fi->sample_rate = h->sample_rate;
> >>+        fi->sample_count = (h->frame_duration * fi->sample_rate)
> /(h->clock_rate * fraction);
> >>+        fi->duration = (double)fi->sample_count / fi->sample_rate;
> >Please  no double  type.
> >Also make use of av_rescale.
>
> Around line 1108 of the avcodec patch, I found the duration was not needed
> and removed it.
>
>
> On 6/13/23 12:04 PM, Anton Khirnov wrote:
> > Also do note that sharing structs across libraries opens you to various
> > compatibility questions [2]. It might be easier to sidestep them by
> > having a function in libavcodec that accepts AVCodecParameters and fills
> > them according to the data, rather than pass codec-specific structs
> > between libavformat and libavcodec.
>
> In line 1061 of the avcodec patch, changed the function to:
>   int av_dtsuhd_frame(DTSUHD *h, const uint8_t *data, size_t data_bytes,
>         AVCodecParameters *codecpar, uint8_t **udts, int *udts_size)
>
>
>
Usually libavcodec code does use get_vlc2() for variable length codes,
instead of
usage of show_bits/skip_bits/get_bits.




>
> Thank you for reviewing this,
> -Roy_______________________________________________
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