Avidemux Forum

Avidemux => Windows => Topic started by: guju on April 09, 2024, 12:54:22 PM

Title: HEVC video generated by OpenCV/ffmpeg shows black screen. Bug?
Post by: guju on April 09, 2024, 12:54:22 PM
Recently I needed to edit a HEVC video that was generated
by standard HEVC output of OpenCV (ffmpeg 5.0.1).

Opening gives no error message but only a black screen.
(Opening it with VirtualDub2 (2020), ffmpeg CLI or MPC-HC: no problem).

Can you tell what is going wrong here?
Is it a bug of ADM? (Or maybe of HEVC-type generated?)

https://c.gmx.net/@1155842887640945833/bJH2qPQ-Tm279HnSREF4SA

EDIT:
It is lossless HEVC.
Title: Re: HEVC video generated by OpenCV/ffmpeg shows black screen. Bug?
Post by: Geo_log on April 10, 2024, 11:24:41 AM
Quote from: guju on April 09, 2024, 12:54:22 PMwhat is going wrong here
- container .avi
Save the output of OpenCV to .mp4 container. 
Title: Re: HEVC video generated by OpenCV/ffmpeg shows black screen. Bug?
Post by: guju on April 10, 2024, 09:28:34 PM
Thank you, HEVC in MP4 is accepted by ADM.

However who's the culprit?

Does OpenCV writes HEVC in MP4 errornous?
(There would be a bug in OpenCV)
Is ADM unable to read HEVC in AVI?
(That would be bug or restriction of ADM)
Title: Re: HEVC video generated by OpenCV/ffmpeg shows black screen. Bug?
Post by: eumagga0x2a on April 10, 2024, 10:31:28 PM
Avidemux currently doesn't understand that codec tag "hev1" means HEVC.

(More precisely, only the MP4 demuxer supports that tag. This is why a placeholder, invalid decoder is chosen when opening this video stored in an AVI container, while an MP4 works.)
Title: Re: HEVC video generated by OpenCV/ffmpeg shows black screen. Bug?
Post by: eumagga0x2a on April 10, 2024, 10:39:43 PM
Tag added, please try a future nightly.
Title: Re: HEVC video generated by OpenCV/ffmpeg shows black screen. Bug?
Post by: guju on April 11, 2024, 07:21:26 AM
That's fine, I'm glad for my little contribute to enhance ADM.
Thank you!  :)
Title: Re: HEVC video generated by OpenCV/ffmpeg shows black screen. Bug?
Post by: guju on April 11, 2024, 11:51:06 AM
Out of curiousity I tried saving hevc/ x265 in avi containter with ADM.

==> "Bad idea. H264/ H265 in AVI... better use MKV".

Is that still up to date, or just a relict?