GoPro Forums banner
1 - 7 of 7 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
I have a Gopro 4 Silver files that look completely different when viewed in different players.

In Quicktime player, Windows media player, Windows photo, iMovie, video looks as expected.
In VLC on both Mac and PC, Davinci Resolve, file looks over - cotrasty and lose some details in shadows and highlights. Heavy editing is required to get a similar look than in Quicktime player.

But, after file is either converted by Handbrake, or exported from Davinci Resolve or iMovie, it is now showing identical in all mentioned players/editors.

SO, there must be something embedded in the Gopro 4 mp4 file that is respected in some software but not in others.

Any advice appreciated. Thanks.
 

·
Registered
Joined
·
517 Posts
some players use their own codecs, nothing to worry about.
 

·
Registered
Joined
·
4 Posts
Different videos use different colour matrices, the most common being Rec.601 for SD content and Rec.709 for HD content. Since this information isn't always embedded in the video metadata, it's up to the player to make assumptions, and sometimes they'll select the wrong colour matrix.
 

·
Registered
Joined
·
2 Posts
Discussion Starter · #5 ·
Thanks. I mentioned players as an example. The issue is that iMovie (and Final Cut Pro) import media differently (like QT player) than Davinci Resolve (like VLC).

Apparently, this is caused by color range (pc, bt709) for GoPro mp4 vs (tv, bt709) which appears to be a standard output for any editor (including both FCP and Davinci Resolve). So the issue is only importing media.

Now, the real issue is that I want to use Davinci Resolve, but imported video is unusable without some serious editing which is not what I want to do.

Also I am not sure which software displays video "correctly". QT player, Windows media player and FCP appear to be "correct", while VLC, Windows DVD player and Davinci Resolve appears over-contrasty with washed out highlights and too dark shadows. But that is "feel" only.
 

·
Registered
Joined
·
4 Posts
A bigger problem with GoPro videos is that their VUI metadata indicates that it's LIMITED-range (16-235) whereas it's FULL-range (0-255). With wrong metadata, only software that ignore this metadata will get it right.
 

·
Registered
Joined
·
4 Posts
I posted more details about why GoPro videos behave inconsistently between decoders here.

It produces invalid H265 files.

To prove it, run FFMPEG to convert a GoPro footage to lossless UT Video
ffmpeg.exe -i GX020100.MP4 -vcodec utvideo -acodec copy GX020100.MKV

It outputs a list of errors.
  • Using non-standard frame rate 29/1
  • deprecated pixel format used, make sure you did set range correctly
  • Duplicate POC in a sequence
  • Error parsing NAL unit #0
  • Error while decoding stream #0:0: Invalid data found when processing input
How a decoder reacts to those inconsistencies depends on the decoder. Some will crash, some will issue warnings, some will make assumptions, some will shift colours, some will skip frames.

I love my GoPro 9, but because of this sloppy programming, I'd look at other options before buying another one unless they fix their firmware.

I don't know whether their H264 video encoding has less bugs. Next time, I'll turn off HEVC, enable high-bit-depth encoding, and re-encode all videos as I transfer them to my PC at a bitrate of my choice.
 
1 - 7 of 7 Posts
Top