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The Raspberry Pi will do hardware accelerated h264 encoding when recording video from the camera board. How can I encode h264 (using hardware acceleration) when the source images are not coming directly from the camera?

Are there any command line tools that support this?

If no, what APIs should I be looking at to make this possible?

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  • What are you encoding, and how so currently? - are you converting video files, rendering them from images and sound, etc... – Wilf Jun 5 '14 at 23:00
  • @Wilf I'm interested in this in general, however I do have a present application: encoding a time lapse directly to video. I can't use raspivid because I need low framerates between 1/5 and 2 fps. Also, raspivid auto-exposure goes into oscillations under my lighting conditions (low light). So I want to use raspistill, but encode directly to video so the result doesn't take up too much space (as JPEGs would). As a second application I want to post process each frame in real time using Mathematica (will take a lot of CPU time), and then send them to be encoded into h264. – Szabolcs Jun 6 '14 at 3:17
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    @Wilf I do have a partial solution which I think should be possible to make work: the idea is something like raspiyuv -o - | rpi-encode-yuv (roughly) where the rpi-encode-yuv tool is from here. The frame size is hard-coded in this tool, so you need to change it at the beginning of the C file and recompile. Unfortunately I haven't managed to get a properly aligned output yet, as raspiyuv doesn't seem to encode the frame size into its output. I get a gradually shifting picture that eventually turns to garbage. Still working on it. – Szabolcs Jun 6 '14 at 3:20
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GStreamer is included in Raspbian and with its OpenMAX plugin it will use the hardware encoding capabilities of the Raspberry Pi.

See this link for a tutorial on doing what you're looking for: https://www.raspberrypi.org/forums/viewtopic.php?t=72435

If you're interested in transcoding, I've just posted an answer to another question that might interest you: What speed can I expect from the hardware-H264-encoding?

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  • Thanks! I cannot test this right now but will accept in advance based on your tutorial. – Szabolcs Apr 12 '15 at 21:34
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Looks like by compiling ffmpeg by yourself, on RPi3B+ you can get

ENCODING HIGH-COMPLEXITY 30 FPS VIDEO FROM A 1920 X 1080 JPEG IMAGE SEQUENCE – SIGNIFICANT MOTION AND INTRAFRAME DETAIL – HIGH QUALITY SETTINGS:

Software-Based H.264 Encoding (CPU): 2.6 FPS (11.5 times slower than real time)

Hardware-Based H.264 Encoding (GPU): 6.3 FPS (4.8 times slower than real time)

ENCODING HIGH-COMPLEXITY 30 FPS VIDEO FROM A 640 X 480 JPEG IMAGE SEQUENCE – SIGNIFICANT MOTION AND INTRAFRAME DETAIL – HIGH QUALITY SETTINGS:

Software-Based H.264 Encoding (CPU): 18 FPS (1.7 times slower than real time)

Hardware-Based H.264 Encoding (GPU): 38 FPS (1.3 times FASTER than real time)

The script to help achieve all this is in a forum thread.

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