8
votes
Accepted
What CRF or settings I should choose for h265 in order to achieve a similiar quality of h264?
The CRF scales for x264 and x265 do not correspond. x265 CRF 28 is supposed to be equivalent to x264 CRF 23. But x265 is not yet as mature in its development as x264, so take that CRF equivalence with ...
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7
votes
restart ffmpeg job from failure
A direct option to resume encoding is not available.
And as for manually restarting encoding, that's also not possible. Two reasons:
1) when transcoding to a typical container like MP4, the index is ...
- 32.6k
6
votes
Accepted
ffmpeg transcoding H264 interlaced and keep interlacing via H264_NVENC codec
It's an issue with new video drivers. Everything is fine with video driver 361.28 and lower.
I already sent this issue to NVIDIA Support with Reference Number 161118-000164
UPDATE: This issue has ...
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5
votes
Why when you specify a video bitrate with ffmpeg does the resulting files displayed bit rate differ?
The issue is that you are using -crf with -b:v. ffmpeg is a well built program, so it's just ignoring -b:v and using -crf. If you want to have a specific bitrate, remove the crf command.
CRF is "...
- 2,164
5
votes
Accepted
How is possible for YouTube and Vimeo transcode so fast?
A common method is split-and-stitch where the file is cut into pieces and sent to multiple servers for transcode. That way you can transcode a file of any length in a fixed amount of time.
...
- 86
5
votes
Accepted
RTSP to RTMP converting fails after specific time only when IP camera enters night mode
I've solved the issue by rebuilding the timestamps from scratch with -use_wallclock_as_timestamps 1 and -fflags +genpts.
/usr/bin/ffmpeg -use_wallclock_as_timestamps 1 -i "rtsp://${source}" -fflags +...
- 191
4
votes
Accepted
what graphics card features effect NVIDIA NVENC hardware encoding speed?
There are two main features in NVIDIA NVENC encoding:
Video memory if you need to transcode many streams.
NVENC SIP - than better this SIP than better encoding performance
is. It depends on GPU. You ...
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4
votes
How can I efficiently convert MOV / MPEG-4 files for long term storage?
Although @stib's advice is sound, I disagree with "to get an appreciable size reduction you would have to throw away a lot of quality". Cameras have to compress on-the-fly, so they use constrained ...
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4
votes
Accepted
Questions on workflow: 12G-SDI to 500Mbps to RTSP stream
I've worked through a similar project over the last 6 months, and performed more tests than I can keep track of now. So this is a little fresh for me. With your questions:
4K camera -> capture ...
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4
votes
Accepted
ffmpeg transpose=clock rotates 180 degrees instead 90
FFmpeg, by default, autorotates videos if a rotation tag is detected. The output video will be oriented upright and have no rotation tag. During processing, this step happens before any filtering is ...
- 32.6k
3
votes
Accepted
Is there a video container which is able to handle segments of different video quality (or even size)?
If the only difference is bitrate, then any container which accepts variable bitrate streams, will fulfill your requirement e.g. MP4, MKV..etc
Step 1 is to encode your segments, ideally using the ...
- 32.6k
3
votes
Converting WMV to MP4
All that matters is if the MP4 looks good to you. Of course, you may be able to compress more. There is no set bitrate to use. More complex or rapidly changing visuals require greater bitrate. Most ...
- 32.6k
3
votes
Accepted
Transcode 5.1 audio in ffmpeg leads to incorrect audio mapping in output
FFmpeg assumes that the input's 5.1 channel mapping is the same as the one it uses. To correct that, use the channelmap filter to remap, add:
-af "channelmap=4|0|1|2|3|5:5.1"
(I based it off the ...
- 32.6k
3
votes
How should I interpret the results from Netflix VMAF
In general, the higher the VMAF score, the higher the quality of the video will be perceived by the viewer. Lower VIF component and ADM scores indicate problems caused by intra-frame compression ...
- 2,405
3
votes
How should I interpret the results from Netflix VMAF
The VMAF models are actually trained by humans who rated the quality on a 1-5 point scale, watching the movie either on an 1080p screen from 3x screen height away, or on a 4k screen from 1.5x screen ...
- 201
3
votes
Intra-frame H.264 / H.265 compared to DNxHR or Prores as intermediate codecs for editing
ProRes/CineForm/DNxHR caught on because of the platforms which decided to use them. Initially, H.264 didn't have 10-bit implementations and H.265 didn't exist.
Those formats are made to hold up to ...
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3
votes
Accepted
Best strategy to keep aspect ratio consistent for all videos having any resolution
If you want the output resolution to be 1280x720 and the video keeps its original ratio aspect as well:
ffmpeg -v error -stats -i input -vf
"scale=1280:720:force_original_aspect_ratio=1,pad=1280:720:...
- 46
3
votes
How to preserve colorspace in ffmpeg
This command preserved the colorspace and also video didnt get darker after transcoding
ffmpeg -i input.mp4 -color_primaries smpte170m -color_trc smpte170m -colorspace smpte170m -r 25 -crf 18 output....
- 151
2
votes
Accepted
FFmpeg transcoding GOP pattern IP
Use
ffmpeg -i INPUT -vcodec libx264 -g 2 -acodec copy -y out.mpg
As per the x264 docs, scenecut=0 disables scenecut evaluation.
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2
votes
Accepted
DVD not displaying full picture
You will need to work within the title safe areas when burning to DVD as depending on what the final player will be, there might be overscan which will/can crop anything out that is not within this ...
- 1,284
2
votes
How do I know if a video file is encoded perfectly or not?
There are several methods/algorithms to compare a transcoded file against its original.
This is a good article which I believe covers what you're asking. It touches on algorithms such as Peak Signal-...
- 121
2
votes
Accepted
Please Explain the Codecs in my Example
So codecs compress and decompress videos, right?
COmpress DECompress. Yep. Just like with text encoding, e.g. ascii or unicode, but with video you take a raster (grid of pixels) and turn that into a ...
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2
votes
Accepted
Converting to Uncompressed Video Files
The answer to your question depends on the software you will use for editing.
Uncompressed RAW video is rarely used for editing for performance reasons. If you have actually recorded your media in 10-...
- 443
2
votes
Accepted
Recover mangled VirtualBox-generated WebM video
After a bit manipulation... You see...
Most easiest way for you:
Write very simple app in C, which will read 1024*768*3 bytes and pads by zeros to 1327*768*3 bytes. It easy for you.
Dump raw pixels ...
- 675
2
votes
Accepted
How to make ffmpeg flush the subtitles in real time while transcoding?
When ffmpeg will flush to output depends on the protocol. For file protocol, atleast 256 kiB data must be waiting, unless it's end of output. So, for text formats, there will be only one payload write....
- 32.6k
2
votes
How should I interpret the results from Netflix VMAF
The numbers don’t mean anything. They only have value when compared to other values. You can compare the results between two encodes of the same file and determine which encode produced better results....
- 1,060
2
votes
Accepted
How to choose the right bitrate, H.264 profile and level for Web Video presentation?
If you are looking to get the best possible quality, encode at the highest bitrates you can factoring file size / upload time.
Regardless of what you bitrate you transcode at; nearly all streaming ...
- 2,477
2
votes
How to concatenate 2 MP4 videos to output of certain bitrate?
Step 4 (first attempt) will work if you re-encode the 2nd video like the first (without the filters).
What's happening is that besides the timescale difference between CC's output and ffmpeg's (which ...
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2
votes
If I use a normal build of ffmpeg how take advantage of video acceleration for scale?
The answer to your second question is yes. Change -c:v libx264 to -c:v h264_nvenc. I use those builds as well. If you use the option -encoders you can see a list of included video and audio codecs.
...
- 106
2
votes
Accepted
ffmpeg: Preserve timecode when converting mov to mp4
After some detective work, I've started using a command line that converts the video and keeps the timecode intact:
ffmpeg -y -i input.mov -map 0:v -map 0:a -c:v mpeg4 output.mp4
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Only top scored, non community-wiki answers of a minimum length are eligible