[Bug 58425] New: video/x-h264 alignment=au caps causes artifacts and crashes with nal-aligned streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

Bug ID: 58425
           Summary: video/x-h264 alignment=au caps causes artifacts and
                    crashes with nal-aligned streams
           Product: Wine
           Version: 10.11
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: winegstreamer
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Multiple applications try to playback nal-aligned streams, but Wine always sets
the alignment caps to au. This causes h264parse to work incorrectly, which in
turn leads to  various unpleasant effects, depending on the decoder used.

Some examples:
- libav's avdec_h264 is the most tolerant one, and only displays brief image
artifacts when au-alignment is broken.
- OpenH264 displays major image and temporal artifacts on au-alignment break,
sometimes hangs.
- NVIDIA's nvh264dec immediately crashes the entire application on au-alignment
break.

This issue is completely fixed by not setting the alignment caps at all and
letting h264parse do it's job, as done in this commit:
https://github.com/ValveSoftware/wine/commit/0304a42

Not sure why it's set in the first place. Maybe that patch can be merged into
Wine master, or is there something that I'm missing?

[Bug 58425] video/x-h264 alignment=au caps causes artifacts and crashes with nal-aligned streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

[e-mail] changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |[e-mail]

[Bug 58425] video/x-h264 alignment=au caps causes artifacts and crashes with nal-aligned streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

--- Comment #1 from Ken Sharp  ---
> Multiple applications

Which ones? It's helpful if there is a download available to test against.
It also helps to attach the bug to the relevant entries in the AppDB.

[Bug 58425] video/x-h264 alignment=au caps causes artifacts and crashes with nal-aligned streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

--- Comment #2 from [e-mail] ---
Mostly CRIWare under Unity. Can't find anything that is both free and public,
but there probably is. I'll try to make a test application to show the issue.

[Bug 58425] video/x-h264 alignment=au caps causes artifacts and crashes with nal-aligned streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

--- Comment #3 from [e-mail] ---
Upon further investigation, the underlying problem appears to be different from
what I first described. Most buffers submitted by CRIWare are actually
au-aligned, but sometimes the last nal is incomplete, and it's continuation is
submitted in the next buffer, after which following buffers are correctly
au-aligned again. Windows can somehow handle this nightmare, but as of now,
Wine cannot. Letting h264parse align the buffers by not setting alignment=au
makes the behavior match Windows.

[Bug 58425] video/x-h264 alignment=au caps causes artifacts and crashes with "almost-aligned" streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

[e-mail] changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|video/x-h264 alignment=au   |video/x-h264 alignment=au
                   |caps causes artifacts and   |caps causes artifacts and
                   |crashes with nal-aligned    |crashes with
                   |streams                     |"almost-aligned" streams

[Bug 58425] video/x-h264 alignment=au caps causes artifacts and crashes with "almost-aligned" streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

--- Comment #4 from [e-mail] ---
Created attachment 78875
  --> http://bugs.winehq.org/attachment.cgi?id=78875
Test program

Here is a test program that demonstrates the problem in a very exaggerated way,
by splitting the last NALU in every AU in half. Test steps:
1. Recode a video to Annex B with e.g. `ffmpeg -i input_video -c:v libx264
-x264-params 'annexb=1:aud=1' -f h264 test.h264`.
2. Try decoding the video with `test_align.exe test.h264 out.bin` on Wine
10.11. If using avdec_h264, you will get lots of buffer overread errors. Verify
artifacts with `ffplay -f rawvideo -video_size WxH out.bin`.
3. Try decoding the video on Windows in the same way. Verify that there aren't
any artifacts with ffplay.
4. Try decoding the video on Wine again, but with the abovementioned patch.
Verify that the characteristic artifacts are not there anymore.

Sidenote: when decoding on Wine, there often appears a green strip at the
bottom of the video. That does not depend on whether the video was
"preprocessed", so it's a different bug.

[Bug 58425] video/x-h264 alignment=au caps causes artifacts and crashes with "almost-aligned" streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

[e-mail] changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |[e-mail]

[Bug 58425] video/x-h264 alignment=au caps causes artifacts and crashes with "almost-aligned" streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

[e-mail] changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |[e-mail]

[Bug 58425] video/x-h264 alignment=au caps causes artifacts and crashes with "almost-aligned" streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

--- Comment #5 from [e-mail] ---
CC Rémi Bernon per git blame, Brendan McGrath as commit author.

[Bug 58425] video/x-h264 alignment=au caps causes artifacts and crashes with "almost-aligned" streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

[e-mail] changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |testcase

[Bug 58425] video/x-h264 alignment=au caps causes artifacts and crashes with "almost-aligned" streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

--- Comment #6 from Brendan McGrath  ---
One of the reasons I felt this was safe for Proton but not for upstream was
because I know 'h264parse' is always available with Proton. For upstream wine
however, it will require the user to install `gst-plugins-bad`.

Without 'h264parse' available, removing the 'au' alignment could make things
worse (I'll need to double check). But even so, there is probably a way to
check if 'h264parse' is missing and then fallback to 'au' alignment in that
scenario.

I'll look in to it.

[Bug 58425] video/x-h264 alignment=au caps causes artifacts and crashes with "almost-aligned" streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

Zeb Figura  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |[e-mail]

--- Comment #7 from Zeb Figura  ---
(In reply to Brendan McGrath from comment #6)
> One of the reasons I felt this was safe for Proton but not for upstream was
> because I know 'h264parse' is always available with Proton. For upstream
> wine however, it will require the user to install `gst-plugins-bad`.
>
> Without 'h264parse' available, removing the 'au' alignment could make things
> worse (I'll need to double check). But even so, there is probably a way to
> check if 'h264parse' is missing and then fallback to 'au' alignment in that
> scenario.
>
> I'll look in to it.

I think depending on h264parse is fine. We need it anyway for other reasons;
cf. 5988.