[mythtv] Mediacodec problem with avcodec_flush_buffers

Peter Bennett pb.mythtv at gmail.com
Fri Jul 27 16:35:25 UTC 2018

On 07/27/2018 10:37 AM, David Engel wrote:
> On Fri, Jul 27, 2018 at 08:09:36AM -0400, Peter Bennett wrote:
>> I think it is only with deinterlace. It may also happen with h264 interlaced
>> content. I do not have much h264 interlaced content to test with.
> I have at least one, 1080i, h264 channel.  I can check it tonight.
> David

I have one 2-minute h264 interlaced 1080 file. I tested with that and I 
do not see the corrupted frame there when skipping.
Attached is a patch to undo the non-functional workaround for the 
corrupted frame in case you want to try it.

>> On 07/26/2018 02:28 PM, Aman Gupta wrote:
>>> Did some tests and it looks like it's mpeg2 issue only.
>>> I forwarded your screenshot to my contact at Nvidia who has filed an
>>> issue with their media team.
>>> Aman
>>> On Thu, Jul 26, 2018 at 9:41 AM Aman Gupta <aman at tmm1.net
>>> <mailto:aman at tmm1.net>> wrote:
>>>      Is it happening with h264 too, or mpeg2 only?
>>>      Aman
>>>      On Thu, Jul 26, 2018 at 8:43 AM Aman Gupta <aman at tmm1.net
>>>      <mailto:aman at tmm1.net>> wrote:
>>>          On Thu, Jul 26, 2018 at 8:18 AM Peter Bennett
>>>          <pb.mythtv at gmail.com <mailto:pb.mythtv at gmail.com>> wrote:
>>>              Hi Aman
>>>              When doing a skip forward in playback, we use
>>>              avcodec_flush_buffers and
>>>              then start processing from a different part of the file.
>>>              We then receive
>>>              a couple of frames from the new location and then one
>>>              which contains
>>>              part of a frame from before the flush and part of a new
>>>              frame. There is
>>>              a diagonal jagged line across the middle. Above the jagged
>>>              line is part
>>>              of an image after the flush. Below the line is part of an
>>>              image before
>>>              the flush. This produces a noticeable irritating flash on
>>>              the screen.
>>>              In this case the second frame after the flush was
>>>              corrupted this way. It
>>>              is not consistent, sometimes the third frame, sometimes a
>>>              later one. I
>>>              tried to compensate by dropping some frames after a flush
>>>              but it is
>>>              problematic because it is inconsistent.
>>>              This link is a photograph of the screen when I stopped it
>>>              during playback.
>>>              https://www.dropbox.com/s/rxub9otpwuop3t9/IMG_20180709_173348703.jpg?dl=0
>>>          I have seen this too. It started when the shield updated to
>>>          Oreo. I'm not sure there's anything we can do about it besides
>>>          reporting to Nvidia.
>>>          Aman
>>>              I have other pictures from before and after the bad one if
>>>              you need them.
>>>              Peter
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