Ffmpeg threads

This article details how the FFmpeg threads command impacts performance, overall quality, ffmpeg threads, and transient quality for live and VOD encoding. Ffmpeg threads we all have learned too many times, there are no simple questions when it comes to encoding. So hundreds of encodes and three days later, here are the questions I will answer.

Opened 10 years ago. Closed 10 years ago. Last modified 9 years ago. Summary of the bug: Ffmpeg ignores the -threads option with libx It is normal for libx to take up more CPU than libx This does not mean that libx is not using multithreading.

Ffmpeg threads

Connect and share knowledge within a single location that is structured and easy to search. What is the default value of this option? Sometimes it's simply one thread per core. Sometimes it's more complex like:. You can verify this on a multi-core computer by examining CPU load Linux: top , Windows: task manager with different options to ffmpeg:. So the default may still be optimal in the sense of "as good as this ffmpeg binary can get", but not optimal in the sense of "fully exploiting my leet CPU. Some of these answers are a bit old, and I'd just like to add that with my ffmpeg 4. In on Ubuntu I was playing with converting in a CentOS 6. Experiments with p movies netted the following:. The interesting part was the CPU loading using htop to watch it. Using no -threads option wound up at the fps range with load spread out across all cores at a low-load level. Using anything else resulted in another spread-load situation.

Well, ffmpeg threads, this feature is awesome for one-off encoding by a home user. As you can see, the quality drops as the thread count increases for a total drop of. The audio stream with most channels viz.

It wasn't that long ago that reading, processing, and rendering the contents of a single image took a noticeable amount of time. But both hardware and software techniques have gotten significantly faster. What may have made sense many years ago lots of workers on a frame may not matter today when a single worker can process a frame or a group of frames more efficiently than the overhead of spinning up a bunch of workers to do the same task. But where to move that split now? Basically the systems of today are entirely different beasts to the ones commonly on the market when FFmpeg was created. This is tremendous work that requires lots of rethinking about how the workload needs to be defined, scheduled, distributed, tracked, and merged back into a final output. Kudos to the team for being willing to take it on.

This article details how the FFmpeg threads command impacts performance, overall quality, and transient quality for live and VOD encoding. As we all have learned too many times, there are no simple questions when it comes to encoding. So hundreds of encodes and three days later, here are the questions I will answer. On a multiple-core computer, the threads command controls how many threads FFmpeg consumes. Note that this file is 60p. This varies depending upon the number of cores in your computer. I produced this file on my 8-core HP ZBook notebook and you see the threads value of For a simulated live capture operation, the value was

Ffmpeg threads

Connect and share knowledge within a single location that is structured and easy to search. I tried to run ffmpeg to convert a video MKV to MP4 for online streaming and it does not utilize all 24 cores. An example of the top output is below. I've read similar questions on stackexchange sites but all are left unanswered and are years old. I tried adding the -threads parameter, before and after -i with option 0, 24, 48 and various others but it seems to ignore this input. I'm not scaling the video either. I'm also encoding in H. Below are some of the commands I've used. I can't figure out what I'm doing wrong or what the bottleneck exactly is.

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Powered by Trac 1. Add a comment. But are there frequent enough tech advances to do that more than a couple of times a year..? Matches streams with usable configuration, the codec must be defined and the essential information such as video dimension or audio sample rate must be present. This may require extra work to be performed upfront. Specify how to set the encoder timebase when stream copying. Note that this option may require buffering frames, which introduces extra latency. Why on earth would you possibly think that? Some devices may provide system-dependent source names that cannot be autodetected. I guess it would be codec dependent, but my understanding is that keyframes are like a synchronization mechanism where the decoder catches up to where it should be in time. I haven't found the command yet, but it does support it.

The libavcodec library now contains a native VVC Versatile Video Coding decoder, supporting a large subset of the codec's features. Further optimizations and support for more features are coming soon.

It's one of several reasons why live streams of this type are often seconds behind live. Browse other questions tagged ffmpeg. To make the second subtitle stream the default stream and remove the default disposition from the first subtitle stream:. This option is thus mainly useful for testing. PreachSoup 3 months ago root parent next [—] Can you run doom on it? GPT has trouble understanding bit masks in single threaded code, let alone multiple threads. While decoders are normally associated with demuxer streams, it is also possible to create "loopback" decoders that decode the output from some encoder and allow it to be fed back to complex filtergraphs. In the above diagram they can be represented by simply inserting an additional step between decoding and encoding:. Indicate to the muxer that fps is the stream frame rate. When used as an output option before an output url , stop writing the output after its duration reaches duration.