In pass 1, output to a null file descriptor, not an actual file.In pass 1 and 2, use the -x265-params pass=1 and -x265-params pass=2 options, respectively.You can also forgo the bitrate calculation if you already know what final (average) bitrate you need.įor two-pass, you need to run ffmpeg twice, with almost the same settings, except for: (200 MiB * 8192 ) / 600 seconds = ~2730 kBit/s total bitrateĢ730 - 128 kBit/s (desired audio bitrate) = 2602 kBit/s video bitrate Your video is 10 minutes (600 seconds) long and an output of 200 MiB is desired. This method is generally used if you are targeting a specific output file size and output quality from frame to frame is of less importance. This uses the native FFmpeg AAC encoder, but under AAC you will find info about more options. This example uses AAC audio at 128 kBit/s. They are explained in the H.264 guide.įfmpeg -i input -c:v libx265 -crf 26 -preset fast -c:a aac -b:a 128k output.mp4 x265 supports the following -tune options: psnr, ssim, grain, zerolatency, fastdecode. By default, this is disabled, and it is generally not required to set a tune option. Ignore placebo as it provides insignificant returns for a significant increase in encoding time. Use the slowest preset you have patience for. Valid presets are ultrafast, superfast, veryfast, faster, fast, medium, slow, slower, veryslow, and placebo. The preset determines compression efficiency and therefore affects encoding speed. CRF works just like in x264, so choose the highest value that provides an acceptable quality. The default is 28, and it should visually correspond to libx264 video at CRF 23, but result in about half the file size.
The mode works exactly the same as in x264, except that maximum value is always 51, even with 10-bit support, so please read the H.264 guide for more info.Īs with x264, you need to make several choices: Use this mode if you want to retain good visual quality and don't care about the exact bitrate or filesize of the encoded file.
In this guide we are going to focus on CRF and Two-Pass encoding, as 1-pass target bitrate encoding is not recommended. 1-pass target bitrate (by setting -b:v).Similar to x264, the x265 encoder has multiple rate control algorithms, including: You can list private options available in this encoder with ffmpeg -h encoder=libx265. You can also download a static build, all of which bundle libx265. The Compilation Guides show you how to do that. See HWAccelIntro for information on supported hardware H.265/HEVC encoders.įfmpeg needs to be built with the -enable-gpl -enable-libx265 configuration flags and requires x265 to be installed on your system. These gains will be most pronounced at resolutions of 1080p and higher. This guide focuses on the encoder libx265 which can offer around 25–50% bitrate savings compared to H.264 video encoded with libx264, while retaining the same visual quality. Final Cut and Apple stuff compatibility.
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