H.264 GStreamer pipelines examples for non-VPU SoCs - Part 1 playback

This post shows some GStreamer pipelines examples for ramping you up on using H.264 on non-VPU SoCs.

All these GStreamer pipelines were tested in the kernel BSP release 4.1.15-2.0.0 GA using i.MX 7Dual SABRE-SD and i.MX 6UltraLite EVK. These pipelines can be also used on other non-VPU SoCs. For installing H.264 plugins in a non-VPU board, please follow this post.

Video Playback

The video used in these tests was big_bucky_bunny_480p_h264.mov.

gst-launch-1.0 filesrc location=<video_file> ! decodebin ! autovideosink

Decodebin and autovideosink choose the decoder plugin and the videosink to be used based on the priority of each plugin installed.

On non-VPU boards, as the process is executed only by the CPU, which can easily reach 100% and cause high system latency, you can face the error There may be a timestamping problem, or this computer is too slow. Some queues can be added with max-size-time property and the sync=false property to the autovideosink to avoid this error. The queue adds some control over the buffer, thereby limiting the frame delay. The sync=false drops the frames which are unlikely to be decoded on time. This option prioritizes the video flow, but might miss some frames:

gst-launch-1.0 filesrc location=<video_file> ! decodebin ! queue max-size-time=0 ! autovideosink sync=false

Camera Playback

gst-launch-1.0 v4l2src device=/dev/video1 ! video/x-raw,width=640,height=480 ! autovideosink

Follow this post to set up the i.MX 6UltraLite EVK camera.

H.264 Software Video Decoder

gst-launch-1.0 filesrc location=<video_file> ! qtdemux ! queue max-size-time=0 ! avdec_h264 ! imxv4l2sink sync=false

This pipeline has the same function as the Video Playback example, but a GStreamer pipeline can be easily modified by the user according to different needs.

H.264 Software Video + Audio Decoder

This example adds audio decoder to the H.264 Software Video Decoder example:

gst-launch-1.0 filesrc location=<video_file> ! qtdemux name=d d. ! queue ! avdec_h264 ! autovideosink sync=false d. ! queue ! beepdec ! alsasink sync=false

H.264 Software Video Encoder

gst-launch-1.0 videotestsrc num-buffers=50 ! 'video/x-raw,format=(string)NV12,width=1280,height=720,framerate=(fraction)30/1' ! x264enc ! mp4mux ! filesink location=video-h264-1280x720.mp4

This example gets the first 50 frames at HD resolution and saves them as a .mp4 file using the H.264 encoder plugin x264enc and mp4mux.

H.264 Software Camera Encoder

gst-launch-1.0 imxv4l2src device=/dev/video1 num-buffers=50 ! videoconvert ! 'video/x-raw,format=(string)NV12,width=640,height=480,framerate=(fraction)30/1' ! queue ! x264enc ! mp4mux ! filesink sync=false location=camera-h264-640x480.mp4

This GStreamer pipeline gets the first 50 frames at VGA resolution and saves them as a .mp4 file using the H.264 encoder plugin x264enc. This is different than the H.264 Software Video Encoder example because x264enc does not support YUY2 colorspace format. This pipeline needs the videoconvert to change YUY2 to NV12.