[Live-devel] MP4 Video Startup Issue

[Bill Barnett]

Hello all,

We are looking for help to determine why the first 7 to 10 seconds of mp4 data video is not displayed in most instances.

Equipment/OS Information:


* Dell Edge Gateway 3001 running Ubuntu 16.04

* Microseven camera - MYM71080i-B with firmware v2.0.11

* Video configuration

[cid:***@01D43AF3.6D727AB0]

openRTSP Information:


* openRTSP v2018.02.18

* Built as: openrtsp_2018.02.18_amd64.snap

* Command line: openRTSP -4 -f 10 -P 30 -F GW_TEST_RUN1-TIME_ rtsp://admin:***@192.168.2.20/12

Problem Information:


* Typically between 200 and 300 seconds (8-10 files) of capture, the files start having 7 to 10 seconds of blank video at the startup. A set of .mp4 files are ready to be supplied, but I did not want to attach 5MB of files here. They show:

o RUN1 - first with blank video is 270-300

o RUN2 - first is 300-330

o RUN3 - first is 240-270

* For each run, I simply killed openRTSP and restarted with another naming convention

o No changes to camera, no power cycles

* The above can be repeated at will every time.

Please let me know where to upload files mentioned above. And, of course, I'm sure I probably haven't provided all the information needed to help.

Thanks very much.

Bill Barnett
President, Software/Firmware Consultant
Jasnik Solutions, Incorporated
***@jasniksolutions.com<mailto:***@neo.rr.com>
330.705.1871<tel:[phone]>

[Ross Finlayson]

The problem here is probably that the stream from your camera is not including I-frames (i.e., ‘key’ frames, consisting of complete pictures) often enough. The captured MP4 file won’t be able to show anything until it sees the first (complete) I-frame.

So, I suggest decreasing the “I-frame interval” in each stream that you want to capture.

Another thing to keep in mind is that these streams will be very sensitive to network packet loss. Each I-frame will take up many RTP packets, and if even one of these RTP packets gets lost on the network, the whole I-frame will be unusable. So, you might also want to play around with decreasing your stream’s bit rate.


Ross Finlayson
Live Networks, Inc.
http://www.live555.com/

[Bill Barnett]

Thanks Ross, this brings up several questions (since I am mainly integrating this into a product as opposed to being an expert).

- Wouldn't we see this problem on all 30 seconds videos, not just starting at file 8 and above (very reproducible)?
- What is the typical frame rate vs I-frame interval that most people use (if there is a "typical")?
- Is there any way to get openRTSP to spit out additional debug data during operation - I did not see this in the docs?
- Is see various mp4 inspectors, is there one that you would recommend that might specifically point to a particular problem?

Thanks much, Bill


-----Original Message-----
From: live-devel [mailto:live-devel-***@ns.live555.com] On Behalf Of Ross Finlayson
Sent: Thursday, August 23, 2018 3:44 PM
To: LIVE555 Streaming Media - development & use <live-***@ns.live555.com>
Subject: Re: [Live-devel] MP4 Video Startup Issue

The problem here is probably that the stream from your camera is not including I-frames (i.e., ‘key’ frames, consisting of complete pictures) often enough. The captured MP4 file won’t be able to show anything until it sees the first (complete) I-frame.

So, I suggest decreasing the “I-frame interval” in each stream that you want to capture.

Another thing to keep in mind is that these streams will be very sensitive to network packet loss. Each I-frame will take up many RTP packets, and if even one of these RTP packets gets lost on the network, the whole I-frame will be unusable. So, you might also want to play around with decreasing your stream’s bit rate.


Ross Finlayson
Live Networks, Inc.
http://www.live555.com/

[Ross Finlayson]

Post by Bill Barnett
Thanks Ross, this brings up several questions (since I am mainly integrating this into a product

A reminder (to everyone) that if you are using the “LIVE555 Streaming Media” software in a product, you are free to do so, as long as you comply with the conditions of the GNU LGPL v3 license; see http://live555.com/liveMedia/faq.html#copyright-and-license


Ross Finlayson
Live Networks, Inc.
http://www.live555.com/

[Warren Young]

Post by Bill Barnett
We are looking for help to determine why the first 7 to 10 seconds of mp4 data video is not displayed in most instances.

Tell whoever wrote that interface that “NTSC” and “720p” are incompatible terms.

As to your question, it’s obvious from the I-frame interval settings combined with the frame rate. The -f flag you gave tells it to select the 10 fps stream, which only puts out a fresh I frame every 10 seconds, given 100 frame GOPs and 10 fps. Until you get a closed GOP and a fresh I frame, the decoder can’t begin decoding, lacking references for most of the delta frame data.

If you want low latency video, you must use a shorter GOP. That will require a higher encoding bit rate to get equivalent perceived quality. TANSTAAFL.

[Ross Finlayson]

Post by Warren Young
The -f flag you gave tells it to select the 10 fps stream

A correction here. openRTSP’s “-f 10” option tells it to *assume* that the frame rate is 10 fps. It doesn’t ‘select’ anything. Of course, it would be meaningful only if the source stream *were* 10 fps.


Ross Finlayson
Live Networks, Inc.
http://www.live555.com/

[Bill Barnett]

So, dumb questions:

- our cameras are manually configured one time at installation for 10 fps, do we even need this on the command line?
- what would happen inside openrtsp in the case of a mismatch?

Thanks very much.

Bill Barnett
President, Software/Firmware Consultant
Jasnik Solutions, Incorporated
***@jasniksolutions.com
330.705.1871

-----Original Message-----
From: live-devel [mailto:live-devel-***@ns.live555.com] On Behalf Of Ross Finlayson
Sent: Thursday, August 23, 2018 4:56 PM
To: LIVE555 Streaming Media - development & use <live-***@ns.live555.com>
Subject: Re: [Live-devel] MP4 Video Startup Issue

Post by Warren Young
The -f flag you gave tells it to select the 10 fps stream

A correction here. openRTSP’s “-f 10” option tells it to *assume* that the frame rate is 10 fps. It doesn’t ‘select’ anything. Of course, it would be meaningful only if the source stream *were* 10 fps.


Ross Finlayson
Live Networks, Inc.
http://www.live555.com/


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[Ross Finlayson]

Post by Bill Barnett
- our cameras are manually configured one time at installation for 10 fps, do we even need this on the command line?

It’s a good idea, because “openRTSP” often can’t figure out the frame rate otherwise.

Post by Bill Barnett
- what would happen inside openrtsp in the case of a mismatch?

It would produce a video file that played at the wrong speed.


Ross Finlayson
Live Networks, Inc.
http://www.live555.com/