[mythtv-users] Status of ffmpeg 4.4.1

[Klaas de Waal]

On Sun, 7 Nov 2021 at 23:44, Peter Bennett <pb.mythtv at gmail.com> wrote:

>
> On 11/6/21 4:20 PM, Klaas de Waal wrote:
>
>
>
> On Sat, 6 Nov 2021 at 14:42, Peter Bennett <pb.mythtv at gmail.com> wrote:
>
>>
>> On 11/6/21 9:02 AM, Klaas de Waal wrote:
>>
>>
>>
>> On Fri, 5 Nov 2021 at 22:49, Klaas de Waal <klaas.de.waal at gmail.com>
>> wrote:
>>
>>>
>>>
>>>
>>> On Fri, 5 Nov 2021 at 21:43, Peter Bennett <pb.mythtv at gmail.com> wrote:
>>>
>>>>
>>>> On 11/5/21 3:17 PM, Klaas de Waal wrote:
>>>>
>>>>
>>>>
>>>> On Wed, 3 Nov 2021 at 20:30, Peter Bennett <pb.mythtv at gmail.com> wrote:
>>>>
>>>>> Most things are working with ffmpeg 4.4.1 in the devel/ffmpeg-resync
>>>>> branch
>>>>>
>>>>> What is not working:
>>>>>
>>>>> - Audio "upconvert stereo to 5.1 sound" when playing a video with
>>>>> stereo
>>>>> sound - error message and no audio playback .
>>>>>
>>>>> - Speedup / slowdown when playing a video with dolby 5.1 audio - error
>>>>> message and no audio playback .
>>>>>
>>>>> - Report from John Pilkington that an existing bug with edit markers
>>>>> and
>>>>> step lengths now reacts slightly differently - I don't know if it is
>>>>> better or worse with the new ffmpeg.
>>>>>
>>>>> I am looking into the 5.1 audio issues.
>>>>>
>>>>> Peter
>>>>>
>>>>>
>>>>> Hi Peter,
>>>>
>>>> As mentioned in the mythtv-dev mailing list, there are with the new
>>>> FFmpeg often blocking artifacts when starting playback and when jumping
>>>> forward and backward.
>>>> This happens also on recordings made with the old FFmpeg so it looks to
>>>> me like a playback-only issue.
>>>> I do see this on my cable TV recordings which are H264, 1080i
>>>> interlaced 50/25 frames per second, both HD and SD.
>>>> I do NOT see this on Bluray rips which are 24p.
>>>> I also do not see this on recordings with MPEG2 video coding, only on
>>>> H264.
>>>>
>>>> Hope you can have a look into this also,
>>>>
>>>> Thanks,
>>>> Klaas.
>>>>
>>>>
>>>>
>>>> I am not able to reproduce this on the devel/ffmpeg-resync branch. I
>>>> tried with NVDEC and with OpenGL playback profiles. Which playback profile
>>>> are you using?
>>>>
>>>>
>>>>  Hi Peter,
>>>
>>> Looks like it happens with VDPAU only. NVDEC, OpenGL and VAAPI (that on
>>> Intel hardware) are OK.
>>> So the failing combination is VDPAU/H264/interlaced.
>>>
>>> Tested some more on other recordings and there are also blocking
>> artifacts with NVDEC, but less pronounced and also sometimes the stream
>> makes a difference. If it is difficult to reproduce I can create a ticket
>> for this and attach photographs and clips.
>>
>> Thanks,
>> Klaas.
>>
>>
>>
>> _______________________________________________
>>
>> Hi Klaas
>>
>> I do not have any H264 interlaced recordings. On Comcast we get MPEG2
>> interlaced and H264 progressive. There is a known problem with MPEG2 and
>> both NVDEC and VDPAU, also NVidia shield where there are frequent
>> pixelations while watching MPEG2, if the stream is highly compressed as
>> some USA channels are. This has been around for many years and NVidia seem
>> to have no plans to fix it.
>>
>> I tried with H264 progressive recordings and I do not see any problem
>> with VDPAU either.
>>
>> Maybe you can send a sample H260 interlaced recording. It will have to be
>> long enough for me to perform skips, if that is the only way to see the
>> problem. What number of seconds do you have for skip ahead and skip back?
>>
>>
>> This is a fragment with the first 100MB of a recent recording, H264 full
> HD interlaced.
>
> https://drive.google.com/file/d/14Z5lsY37wgr5vuL7bg7CyDDO-wg0SWIx/view?usp=sharing
>
> Playing from the start already gives blocking artifacts, as shown in the
> following link
>
> https://drive.google.com/file/d/1UA_m9gEkcrhTe_KfKfTkgKT_MdNDknyL/view?usp=sharing
> This is a screenshot taken immediately after the start of playback at the
> beginning of the file.
> Jumping is configured here for 45 seconds forward and 15 seconds backward
> but it should not matter for reproducing.
>
> FYI, Here on my local cable all HD channels are 1080 interlaced, all SD
> channels are MPEG2 interlaced. The MPEG2 recordings play OK.
> Bluray, 24p, plays OK. I can also receive OTA a 1080 progressive with H265
> coding. This also plays OK.
> I use Nvidia GT1030 cards for playback; in the living room on Ubuntu
> 18.something and the development system on Fedora 35.
>
> I do hope the links do work.
>
> Thanks,
> Klaas.
>
>
>
> I downloaded the file and I can see the problem with VDPAU. It seems ok
> with NVDEC. I am not sure of the best way to fix this.
>
> NVDEC is a better replacement for VDPAU.
>
> VDPAU does not support H265 (hevc). NVDEC supports H265.
>
> If you play H265 with VDPAU and display playback data you will see it has
> reverted to software decoding. 4K H265 video played that way will struggle
> to keep up.
>
> Playing H265 with NVDEC shows that it is using hardware decoding.
>
> I will look at this further to see if I can find what is going on with the
> H264 interlaced
>
>
> Hi Peter,

Glad you are looking into this!
I do fully agree that NVDEC is the way forward, but as I understand it
there are older cards that do support VDPAU but not NVDEC. Also there is
the ATSC CC support which is not yet working for NVDEC. So I think VDPAU
should be supported for a while.
But, also NVDEC playback is not correct. It does depend on the channel,
some skip correct and some skip not. Apparently not all 1080i50 is equal.
Attached is a clip from Eurosport which does show the blocking artifacts
when skipping with NVDEC; decoding with NVDEC verified by the playback
window.

https://drive.google.com/file/d/1bp5-f8FGLMuR_mHtLbRVehYO2olSO9nP/view?usp=sharing

It is definitely only happening with H264 interlaced material; MPEG2 is
always correct and H265 progressive is also correct. I do not have H265
interlaced material.

Hope this helps,
Klaas.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mythtv.org/pipermail/mythtv-users/attachments/20211108/f498b933/attachment.htm>