FFMPEG Tutorial: 2-Pass & CRF In X264 & X265 - Gists · GitHub

Skip to content Search Gists Search Gists All gists Back to GitHub Sign in Sign up Sign in Sign up Dismiss alert {{ message }}

Instantly share code, notes, and snippets.

hsab/ffmpeg_tut_.md Last active November 24, 2025 11:37 Show Gist options

• Download ZIP

• Star 14 (14) You must be signed in to star a gist
• Fork 2 (2) You must be signed in to fork a gist

• Embed Select an option
  • Embed Embed this gist in your website.
  • Share Copy sharable link for this gist.
  • Clone via HTTPS Clone using the web URL.

  No results found

  Learn more about clone URLs Clone this repository at <script src="https://gist.github.com/hsab/7c9219c4d57e13a42e06bf1cab90cd44.js"></script>
• Save hsab/7c9219c4d57e13a42e06bf1cab90cd44 to your computer and use it in GitHub Desktop.

Code Revisions 20 Stars 14 Forks 2 Embed Select an option

• Embed Embed this gist in your website.
• Share Copy sharable link for this gist.
• Clone via HTTPS Clone using the web URL.

No results found

Learn more about clone URLs Clone this repository at <script src="https://gist.github.com/hsab/7c9219c4d57e13a42e06bf1cab90cd44.js"></script> Save hsab/7c9219c4d57e13a42e06bf1cab90cd44 to your computer and use it in GitHub Desktop. Download ZIP FFMPEG Tutorial: 2-Pass & CRF in x264 & x265 Raw ffmpeg_tut_.md

Google FFMPEG H264

Two-Pass: Requires a bitrate. This defines the quality of the video. Youtube and Vimeo usually reduce your bitrate to 25mbs. So if it is higher, it will be compressed by these websites.

Lower bitrate means lower files size.

Calculating Bitrate:

• (Size in Megabytes * 8192) / Total Length in Seconds = Available bandwith
• Available bandwith - Audio Bitrate = Video Bitrate

For example:

• (200 MiB * 8192 [converts MiB to kBit]) / 600 seconds = ~2730 kBit/s total bitrate
• 2730 - 320 kBit/s (desired audio bitrate) = 2410 kBit/s video bitrate

Procedure:

2 Pass example:

• Download FFMPEG fro Windows

• Extract and go to "bin" folder.

• In "bin" hold Shift+RightClick and select Open PowerShell...

• For pass 1: .\ffmpeg.exe -thread_queue_size 512 -y -r 24 -i "D:\%04d.png" -i "D:\Max.wav" -c:v libx264 -pix_fmt yuv420p -vprofile high422 -vlevel 4.2 -preset veryslow -b:v 2410k -c:a aac -strict experimental -b:a 320k -pass 1 -f mp4 NULL

• For pass 2: .\ffmpeg.exe -thread_queue_size 512 -r 24 "D:\%04d.png" -i "D:\Max.wav" -c:v libx264 -pix_fmt yuv420p -vprofile high422 -vlevel 4.2 -preset veryslow -b:v 2410k -c:a aac -strict experimental -b:a 320k -pass 2 "D:\output.mp4"

CRF example:

• Lossy CRF (1-51): .\ffmpeg.exe -thread_queue_size 512 -r 24 -i "D:\%04d.png" -i "D:\Max.wav" -c:v libx264 -pix_fmt yuv420p -vprofile high422 -vlevel 4.2 -preset veryslow -crf 2 -c:a aac -strict experimental -b:a 320k "D:\crf2_output.mp4"

• Lossless CRF 0 H264: .\ffmpeg.exe -thread_queue_size 512 -r 24 -i "D:\%04d.png" -i "D:\Max.wav" -c:v libx264 -pix_fmt yuv444p -vprofile high444 -vlevel 5.1 -preset veryslow -crf 0 -c:a aac -strict experimental -b:a 320k "D:\crf0_output.mp4"

• Lossless CRF 0 H265: .\ffmpeg.exe -thread_queue_size 512 -r 24 -i "D:\%04d.png" -i "D:\Max.wav" -c:v libx265 -preset veryslow -crf 0 -c:a aac -strict experimental -b:a 320k "D:\crf0_output.mp4"

Parameters Explained:

Framerate of Source: -r 24

Source Video: -i "D:\%04d.png" (Image Sequence eg 0001.png)

Source Audio: -i "D:\Max.wav"

Codec Video: -c:v libx264

Pixel Format: -pix_fmt yuv420p

H264 Profile: -vprofile high422

H264 Level: -vlevel 4.2

Compression (Loseless): -preset veryslow

Bitrate Video: -b:v 2410k (Calculated as above)

Pass Number: -pass 1

Codec Audio: -c:a aac

Needed For AAC: -strict experimental

Bitrate Audio: -b:a 320k (Desired audio rate)

Format: -f mp4

Copy link

slycordinator commented May 17, 2023

According to https://trac.ffmpeg.org/wiki/Encode/H.264 the conversion factor for bitrates should be 8388.608.

In ffmpeg, bitrates are given in "kb/s" and according to the documentation, kb is 1000 bits. But using a factor of 8192 gives you kibibits (1024 bits).

Uh oh!

There was an error while loading. Please reload this page.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment You can’t perform that action at this time.