[FFmpeg-devel] [PATCH] hevc - fix split function of parser

[Hendrik Leppkes]

On Fri, Sep 25, 2015 at 2:46 PM, Ståle Kristoffersen
<staalebk at ifi.uio.no> wrote:
> On 2015-09-01 at 16:27, Rainer Hochecker wrote:
>>
>> fix splitting extradata from ts
>
> Hi,
> this commit introduces a regression for me.
> I'm trying to extract a thumb from the middle of a live TS, containing one
> HEVC-stream.
> Unfortunately I'm not sure if I can provide a sample, but before this patch
> I would always get a good looking thumb, but with this patch I would for
> the most part get a mostly gray frame.
>
> If I generates a few more thumbnails i see that it eventually spits out the
> same frame that ffmpeg before this patch produced as the first thumb, and
> it looks OK.
>
> However it is much more blocky than what the previous ffmpeg produced:
> This is the command I want to run:
>
> ffmpeg -nostdin -y -an -i hevc_fail.ts -vframes 1 -vf scale=iw*sar:ih thumb%d.jpg -v 100
>
>
> Before this patch:
> http://kolbu.ws/~chiller/thumb1.jpg
>
> with this patch:
> http://kolbu.ws/~chiller/thumb1.62bd8deef9005dbc9750e3bdc12fbf9b50392adc.jpg
>
> If i let it generates a few more thumbs I end up with a "good" thumb:
> http://kolbu.ws/~chiller/thumb18.62bd8deef9005dbc9750e3bdc12fbf9b50392adc.jpg
>
> However, if you compare the two you will see that even the good thumb with
> this patch is much more blocky.

It seems unlikely that this patch is the cause of that, but regardless
- please open an issue on Trac, preferably with a small sample and
command line to test the difference.

- Hendrik