Why is encoding required for video transfer? (gstreamer)

Question

The video I transferred is already encoded. Why do I encode again when transferring?

example: gst-launch-1.0 -v filesrc location=123.mp4 ! decodebin ! x264enc ! rtph264pay ! udpsink host=192.168.10.186 port=9001

Just send the video without encoding. Can I view it on the other side?

for example:

server: gst-launch-1.0 -v filesrc location =123.mp4 ! udpsink host=192.168.10.186 port=9001

123.mp4 encoded h265

client: gst-launch-1.0 udpsrc port=9001 caps = "application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H265, payload=(int)96" ! rtph265depay ! h265parse ! nvh265dec ! autovideosink

best regards

Your question isn't entirely clear... * In the example encoding pipeline, you're streaming out an RTP/H.264 stream. * In the decoding pipeline, you're expecting an RTP/H.265 stream. * You say you don't want to re-encode, but that would mean streaming MPEG.4 (or the specific video subformat, which can be either of the previous, or another codec) — nielsdg
The commands I wrote were just examples: my pipiline in real scenario: sender: gst-launch-1.0 -v filesrc location = 123.mp4! decodebin! video / x-h265! rtph265pay! udpsink host = 192.168.10.186 port = 9001 Receiver: gst-launch-1.0 udpsrc port = 9001 caps = "application / x-rtp, media = (string) video, clock-rate = (int) 90000, encoding-name = (string) H2645"! rtph265depay! h265parse! nvh265dec! autovideosink sync = false — Muratakaydin
My question: 123.mp is already a compressed video as h265. why do we encode again when sending the video? Can't we send the compressed video directly without encoding and decode it by Receiver? — Muratakaydin

nielsdg nielsdg · Accepted Answer · 2020-06-04T16:39:09

Okay, with the clarification that your input is assumed to be an MPEG4 file which contains an H.265: yes, then it's possible (if this is assumption doesn't hold, then this will not work).

The following should do the trick:

gst-launch-1.0 filesrc location=123.mp4 ! qtdemux ! h265parse config-interval=-1 ! rtph265pay  ! udpsink host=192.168.10.186 port=9001

Explanation:

the qtdemux will demux the MPEG4 container into the contained video/audio/subtitile streams (if there's more than one stream inside that container, you'll need to link to it multple times, or GStreamer will error out)
the h265parse config-interval=1 will make sure that your contains the correct SPS/PPS parameter sets. If the stream inside your original input file is not an H265 video stream, this will fail to link.
the rth265pay will translate this into RTP packets.
... which the udpsink can then send over the specified socket

P.S.: you might also be interested in the rtpsink (which used to live out-of-tree, but is now included in the latest master of GStreamer)

P.P.S.: you should use an even port to send an RTP stream

Why is encoding required for video transfer? (gstreamer)

1 Answers