Recherche avancée

Sur d’autres sites (7617)

• How can I do videos into a better format without losing resolution and quality ?

  3 juillet 2020, par Melissa

  I have the job of developing a video converter program. I started to do a lot of research and development on this subject. I currently have a problem like this. The videos of the institution where I developed the converter are in mxf 50 megabit 4 : 2 : 2 format.
They want me to turn these videos into a better format without losing resolution and quality. For example, they said I could try h.265. In my work, the resolution and the quality of the video change in direct proportion when the format changes, how can I overcome this with an algorithm ? As I have just learned about the FFMPEG library, my view may be limited in this area. I am waiting for your help.

  


• ffmpeg - Timecode & Fractional Frame Rate (Duplicating Frames)

  29 mars 2018, par Nimble

  I record two different frame rates using ffmpeg, 60 and 100. Or at least I thought I was recording 60 and 100, now it seems it’s actually 59.94 and 99.98.

  Here is the command I was using :

  ffmpeg -y -thread_queue_size 9999 -guess_layout_max 0 -f dshow -video_size 1920x1080 -rtbufsize 2147.48M -framerate 60 ^
  
  -pixel_format yuyv422 -i video="Game Capture HD60 S (Video) (#01)":audio="ADAT (5+6) (RME Fireface UC)" -map 0:0,0:1 ^
  
  -map 0:1 -c:v h264_nvenc -preset: llhp -pix_fmt yuv420p -b:v 40M -minrate 40M -maxrate 40M -bufsize 40M -b:a 384k -ac 2 ^
  
  -r 60 -af "pan=mono|c0=c0, adelay=84" -vsync 1 -max_muxing_queue_size 9999 -f segment -segment_time 600 ^
  
  -segment_wrap 9 -reset_timestamps 1 C:\Users\djcim\Videos\PC\Camera\CPC%02d.ts ^
  
  -thread_queue_size 9999 -f dshow -video_size 3440x1440 -rtbufsize 2147.48M -framerate 100 -pixel_format nv12 ^
  
  -itsoffset 00:00:00.215 -i video="Video (00 Pro Capture HDMI 4K+)" -thread_queue_size 9999 -guess_layout_max 0 -f dshow ^
  
  -rtbufsize 2147.48M -i audio="SPDIF/ADAT (1+2) (RME Fireface UC)" -map 1:0,2:0 -map 6:0 -c:v h264_nvenc -preset: llhp ^
  
  -pix_fmt nv12 -b:v 250M -minrate 250M -maxrate 250M -bufsize 250M -b:a 384k -ac 2 -r 100 -af "adelay=141|141" -vsync 1 ^
  
  -max_muxing_queue_size 9999 -f segment -segment_time 600 -segment_wrap 9 -reset_timestamps 1 ^
  
  C:\Users\djcim\Videos\PC\PC\PC%02d.ts

  I thought all was well with my frame rates, sure ffmpeg was duplicating frames every once in a while, but I thought it was just a random occurrence caused by ffmpeg dropping a frame during processing and therefore needed to duplicate one to make it up. I didn’t think duplicating a few frames would be noticeable in the footage... until I was reviewing some from the first output, which is actually a camera, and noticed very slight stutters consistently 3 times a minute. This began to bug me, it was very noticeable and I wanted smooth footage. A bit confused I decided to try the first output by itself and watch ffmpeg to see when frames were being duplicated and found that it was duplicating frames every 17 second (16.66 to be more precise).

  After doing the math (1/16.66=.06) I realized that the frame rate of that first capture card was actually 59.94. Doing the same thing for the other output I found that my "100fps" footage is actually 99.98. But what does that really entail ?

  Should I change the fps to 59.94 and 99.98 ? Wont that cause synchronization issues as 99.98 (100*.0002=99.98) isn’t the same standard as 59.94 (60*.001=59.94) ? Or does that mean I just need to set the second output to 99.9 (100*.001=99.9) to match the standard of the first output and drop frames ? If that is the case does this mean in my editing program, Adobe Premiere, I would need to export the final video as 59.94fps not 60fps to avoid duplication of frames ? Or is there some method within timecode that remedies this issue ?

  I guess I just really don’t understand drop frame and non-drop frame timecode / timecode in general. Up until yesterday when something said 60fps I thought it meant literally 60fps but I guess 99% of the time it actually means 59.94. I’d really like to just avoid the duplication of frames as it ruins what would be a smooth experience but don’t know if I can while trying to keep everything synchronized.

  Any help or insight would be appreciated, sorry if my question is a bit confusing I am undoubtedly confused.

• Blender VSE Audio out-of-sync when animation (video) is rendered

  21 août 2021, par Siddhant Shenoy

  Ok, so I found out that Blender has this really cool video-editing interface and I was beginning to love it. Until, I created this awesome project composition and when I exported the animation as a video file, the audio was out of sync :(.

  



  Actual Problem

  



  Audio is in-sync with video when the animation is played in Blender but is out-of-sync in the rendered video.

  



  Solutions I tried out and failed

  



  

  • I used the 'Audio-Sync' option in the sequencer but that made no difference.

  


  • Then I thought that my scene audio frequency might have been an issue since it was initially 48kHz and my videos were at 24kHz, so I changed the scene audio frequency to 24kHz, this still failed to solve the issue.

  


  • Initially, I was combining videos with different frame rates and thought that might have been an issue (although animation played as expected in Blender), so I recreated the source videos to ensure all videos I was using in my project had the same frame rate, but this also did not work.

  


  • Someone online suggested exporting the video and audio separately and then combining them using a command-line tool like FFMPEG, this also failed.

  


  



  What's really frustrating

  



  


  • This lag (audio is a few frames ahead of the video) is noticeable only in longer videos (>12 mins, my video is 1 hr long) suggesting a very small rendered rate difference between the video and the audio.

  


  • Also, note that the animation plays absolutely fine in Blender, so all I could figure out was that this was a rendering issue.

  


  



  So if anyone figured this out please let me know. I am a noob in video/audio codecs so please forgive me if I used some incorrect nomenclature above.