minih264

Small, but yet reasonably fast H264/SVC encoder single-header library with SSE/NEON optimizations. Decoder can be popped up in future.

Disclaimer: code highly experimental.

Comparison with x264

Rough comparison with x264 on an i7-6700K:

x264 -I 30 --profile baseline --preset veryfast --tune zerolatency -b 0 -r 1 --qp 33 --ipratio 1.0 --qcomp 1.0 -o x264.264 --fps 30 vectors/foreman.cif --input-res 352x288 --slices 1 --threads 1

vs

./h264enc_x64 vectors/foreman.cif

| x264 | minih264 | | ------------ | -------- | | source: ~4.6mb | 409kb | | binary: 1.2mb | 100kb | | time: 0,282s | 0,503s | | out size: 320kb | 391kb |

PSNR:

x264:     PSNR y:32.774824 u:38.874450 v:39.926132 average:34.084281 min:31.842667 max:36.630286
minih264: PSNR y:33.321686 u:38.858879 v:39.955914 average:34.574459 min:32.389171 max:37.174073

First intra frame screenshot (left-to-right: original 152064, minih264 5067, x264 5297 bytes):

You can compare results in motion using ffplay/mpv players on vectors/out_ref.264 and vectors/x264.264 .

Usage

TBD

SVC

Minih264 supports both spatial and temporal layers. Spatial layers are almost same as encode 2 independent AVC streams except for Intra frames prediction. Following diagram shows minih264 SVC scheme for two spatial layers:

That's because P frames spatial prediction are almost useless in practice. But for Intra frames there is a ~20% benefit in full resolution frame size. Note that decoder must have both base layer I frame and full resolution SVC I frame to decode whole sequence of next P frames in full resolution.

Limitations

The following major features are not supported compared to x264 (baseline):

• Trellis quantization.
• Select prediction mode using Sum of Absolute Transform Differences (SATD).
• 4x4 motion compensation.

Interesting links

• https://www.videolan.org/developers/x264.html
• https://www.openh264.org/
• https://github.com/cisco/openh264
• http://iphome.hhi.de/suehring/tml/
• https://github.com/oneam/h264bsd
• https://github.com/fhunleth/hollowcore-h264
• https://github.com/digetx/h264_decoder
• https://github.com/lspbeyond/p264decoder
• https://github.com/jcasal-homer/HomerHEVC
• https://github.com/ultravideo/kvazaar
• https://github.com/neocoretechs/h264j
• https://github.com/jcodec/jcodec