[mythtv] 20180705 Android Observations

[Aman Gupta]

On Fri, Jul 13, 2018 at 2:31 PM Peter Bennett <pb.mythtv at gmail.com> wrote:

>
>
> On 07/12/2018 05:43 PM, Peter Bennett wrote:
> >
> >
> > On 07/12/2018 03:42 PM, Aman Gupta wrote:
> >> FWIW I am not able to reproduce this issue with mpv-android. Are you
> >> maybe calling ffmpeg APIs from different native threads?
> >>
> >> Aman
> >>
> > We have a decoder thread. All ffmpeg calls should be done from there.
> > I looked at it and it looks correct. For a next step I will add some
> > logging to make sure all the calls are coming from the same thread.
> >
> > Peter
> I added logging of the calls and confirmed that all of the send, receive
> and flush calls are on the same thread.
>
> This is what I see from the more detailed logging.
> The IllegalStateException came from a receive_frame. The sequence is
>
> flush
> receive frame returns EAGAIN
> send packet
> receive frame returns EAGAIN
> send packet
> REPEAT receive and send until receive frame returns data.
> After about 15 packets have been sent the next send packet returns
> EAGAIN and receive_frame returns EAGAIN. It tries receive_frame again
> and gets the IllegalStateException and the return code of Generic error
> in an external library. Any further operations including flush continue
> to get IllegalStateException and return Generic error in an external
> library.
>
> This seems bogus. If the flush caused an illegal state it should be
> reported on the first send of data after the flush. But it is happy
> receiving 15 packets before suddenly deciding it is in an illegal state.
>
> In the cases where flush works (95% of the time it works correctly), the
> above sequence also occurs, but after send and receive both return
> EAGAIN, the next receive_frame returns a frame correctly, as do
> subsequent receive_frame calls.
>
> I also saw one case of the following error from flush:
>
> [amediacodec @ 0x205ceea118] android.media.MediaCodec$CodecException:
> Error 0xffffffe0
> [mpeg2_mediacodec @ 0x205ced1378] Failed to flush codec
> This was followed by the IllegalStateException on the very next
> receive_frame.


This CodecException is what we need to get to the bottom of. The MediaCodec
docs say you can expect them to happen, and details how to get more
information and check the type of exception (transient, recoverable) and
how to deal with each type when it is received.

Aman

>
>
> This occurred when we did the flush and sent a bunch of packets as
> above. Before getting to the point of send and receive both returning
> EAGAIN, we started a new flush and got this error.
>
> Peter
>
>
>
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