Ffmpeg threads

This article details how the FFmpeg threads command impacts performance, overall quality, and transient quality for live and VOD encoding, ffmpeg threads. As we all have learned too many times, there are no simple questions when it comes to encoding.

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.

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. As you can see, there's also a point of diminishing returns, so you'd have to adjust the -threads option for your particular machine. For my setup specifically, using the -threads 6 on a 12 core machine resulted in the best FPS when converting the video from h to x at a different bitrate to force a conversion and returns actually diminished the more threads I threw into it.

Check the presets directory in the FFmpeg source tree for examples.

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. With both builds Zeranoe and mine and both commands, i've got the same problem with -threads option: it uses both threads instead only one.

Anything found on the command line which cannot be interpreted as an option is considered to be an output url. Selecting which streams from which inputs will go into which output is either done automatically or with the -map option see the Stream selection chapter. To refer to input files in options, you must use their indices 0-based. Similarly, streams within a file are referred to by their indices. Also see the Stream specifiers chapter. As a general rule, options are applied to the next specified file. Therefore, order is important, and you can have the same option on the command line multiple times. Each occurrence is then applied to the next input or output file. Exceptions from this rule are the global options e. Do not mix input and output files — first specify all input files, then all output files.

Ffmpeg threads

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. Thanks to a major refactoring of the ffmpeg command-line tool, all the major components of the transcoding pipeline demuxers, decoders, filters, encodes, muxers now run in parallel. This should improve throughput and CPU utilization, decrease latency, and open the way to other exciting new features. Note that you should not expect significant performance improvements in cases where almost all computational time is spent in a single component typically video encoding. FFmpeg 6. Some of the highlights:.

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Sounds like something we'll have next year, and certainly within a decade. For those of us who write code, this can be useful! Like the linux kernel? Google translates detection and replacement is so much ahead my current image system I'd think I would just somehow reutilize that for my app, either thru public API or browser emulation When the video is being transcoded rather than copied and -autorotate is enabled, the video will be rotated at the filtering stage. Any message related to possibly incorrect or unexpected events will be shown. I have only the vaguest understanding of how it works and it's probably wrong and to my layman mind it also seems like a totally fair assumption, based on experience as a user and the constant flood of news. Modified 2 months ago. Please use the scale filter directly to insert it at the beginning or some other place. Just as writing shitty react apps follow patterns, low-level performance and concurrency work also follow patterns. Using anything else resulted in another spread-load situation.

Connect and share knowledge within a single location that is structured and easy to search. What is the default value of this option?

You can verify this on a multi-core computer by examining CPU load Linux: top , Windows: task manager with different options to ffmpeg:. As an input option, blocks all data streams of a file from being filtered or being automatically selected or mapped for any output. In other words, it's already a multi-core job. These can be part of a custom hook or a utility function with configurable parameters. For subtitles, it will select stream 2 from B. The resulting output file test It is to be expected that ffmpeg then will be able to use as many threads as parallization allows for — which depends on the task given to ffmpeg. What they decided to parallelize is ffmpeg itself. Kudos to the team for being willing to take it on. If the sync reference is the target index itself or -1 , then no adjustment is made to target timestamps. The transcoding process in ffmpeg for each output can be described by the following diagram:. I will say that very few of these discrepancies actually produced frames so ugly that viewers would notice, but several did. I have some snake oil to sell you. With threads 2 or 8 uses the same CPU.