On 24/05/18 07:29, Xiang, Haihao wrote:
> On Wed, 2018-05-23 at 03:27 +0200, Michael Niedermayer wrote:
>> On Mon, May 21, 2018 at 11:07:34PM +0100, Mark Thompson wrote:
>>> On 16/05/18 08:19, Haihao Xiang wrote:
>>>> In lavc/hevec_vaapi, colour properties in AVCodecContext are needed to
>>>> write the sequence header
>>>>
>>>> Tested by the command below:
>>>> ffmpeg -hwaccel vaapi -hwaccel_device /dev/dri/renderD128
>>>> -hwaccel_output_format vaapi -i input-with-hdr.mkv -c:v hevc_vaapi
>>>> -profile:v main10 output.h265
>>>>
>>>> Signed-off-by: Haihao Xiang <haihao.xi...@intel.com>
>>>> ---
>>>> fftools/ffmpeg.c | 4 ++++
>>>> 1 file changed, 4 insertions(+)
>>>>
>>>> diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
>>>> index 5a19a09d9a..80b5441f8f 100644
>>>> --- a/fftools/ffmpeg.c
>>>> +++ b/fftools/ffmpeg.c
>>>> @@ -3298,6 +3298,10 @@ static int init_output_stream_encode(OutputStream
>>>> *ost)
>>>> dec_ctx = ist->dec_ctx;
>>>>
>>>> enc_ctx->chroma_sample_location = dec_ctx-
>>>>> chroma_sample_location;
>>>> + enc_ctx->color_range = dec_ctx->color_range;
>>>> + enc_ctx->color_primaries = dec_ctx->color_primaries;
>>>> + enc_ctx->color_trc = dec_ctx->color_trc;
>>>> + enc_ctx->colorspace = dec_ctx->colorspace;
>>>> } else {
>>>> for (j = 0; j < oc->nb_streams; j++) {
>>>> AVStream *st = oc->streams[j];
>>>>
>>>
>>> There are outstanding patches passing color_range through the filter chain
>>> (see <https://lists.ffmpeg.org/pipermail/ffmpeg-devel/2018-May/229248.html>)
>>> , and that would be the right solution for the rest of these properties as
>>> well, but it would require significantly more work.
>>>
>>> I think hacking it like this is ok for now? It's not worse than before
>>> since a change during filtering wasn't visible anyway, and the manual
>>> options do still work to override it. I think the commit message could be a
>>> little clearer about the problem (really, that this colour information
>>> doesn't pass through filtering) and its limitations (requires a single input
>>> matched to the output; will write the wrong thing if filtering changes
>>> anything) though, or maybe that could be explained in a comment.
>>>
>>> Does anyone else have any thoughts on this? If there are no objections then
>>> I would apply it updated with a clearer explanation.
>>
>> I think the key question is
>> Does this change "Unknown" to incorrect values
>
> Do you mean the color in dec_ctx may be incorrect? If so, we should fix the
> decoder.
No, I mean where the input properties in the decode context are correct but
don't match the output because it gets changed during filtering.
For example:
ffmpeg -i bt709_input.mkv -vf colorspace=bt2020 bt2020_output.mkv
will have the output file marked as BT.709 after this patch, where previously
it was "unspecified". (Explicitly setting
-color_primaries/-color_trc/-colorspace on the output works in both cases.)
- Mark
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