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First 90 secs of the video showing only black.

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Prathamesh Sathaye
First 90 secs of the video showing only black.
on Sep 5, 2015 at 7:38:32 pm

Hi All, hope I am posting in the right forum.

I have delivered a video file to my client as per his requirement as below :

Mpeg 2 Transport stream with :

H.264 video Main@L 3.2
Frame rate : 29.97
Resolution : Full D1 , 16:9 Anamorphic
Bitrate : CBR 1500 kbps
CABAC = Yes
Gop length = 15, B frames =2 , Closed GOP, Reference frames =2, No weight prediction, No adaptive B frames.
Buffer length = 1000 ms

aac lc Audio : Stereo, 128 kbps, 44.1 kHz.

I used Digital Rapids Streamz for the above.

The Video and Audio streams were muxed into mpeg 2 ts using Manzanita mp2tsme muxer with overall bitrate of 1863 kbps.

The source video is 25fps ProRes 422 with a 3 seconds black at the start.

My client says the first 90 seconds of the file show only a black screen before the video plays.

I am not able to figure out what is causing the 90 seconds delay in playing the file. I didn't give any delay when muxing either.

Guys, any suggestions pls.
Regards.


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Craig Seeman
Re: First 90 secs of the video showing only black.
on Sep 5, 2015 at 8:42:47 pm

How is your client playing the file?
How are you playing the file?
Can your client give you a working file to analyze? Can the client tell you how such file was created?
Can you try the same specs with a different encoder (even a trial version)?



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Prathamesh Sathaye
Re: First 90 secs of the video showing only black.
on Sep 5, 2015 at 9:35:43 pm

Hi Craig,

I have played the file on VLC,MPC,Elecard Mpeg player. It plays just fine.

Digital Rapids is the only encoder we have at the lab.

My Client provides Inflight Entertainment solutions, so he tests the video files on his hardware device.

I have previously delivered video content to him with the same above specs and it worked fine.

My client says, the only feedback he can give is there is a buffer flush, causing the 90 secs black before the video plays.

I have no idea what is causing the buffer flush, since I didnt get any buffer underflow errors when muxing.


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Craig Seeman
Re: First 90 secs of the video showing only black.
on Sep 5, 2015 at 11:27:23 pm

[Prathamesh Sathaye] " have played the file on VLC,MPC,Elecard Mpeg player. It plays just fine."
[Prathamesh Sathaye] "My Client provides Inflight Entertainment solutions, so he tests the video files on his hardware device."

Which may mean your playback devices aren't representative of his playback device. Perhaps VLC etc. is much more forgiving.

[Prathamesh Sathaye] "I have previously delivered video content to him with the same above specs and it worked fine."
Which means
Something changed on your end such as software update
Something changed on the client's end such as software or firmware update
The encoded file is bad.

Since you must explore the cause to fix the problem you're options are:
1) Re-encode the file again to see if it's an issue with the encode.
2) Test with another file to see if the issue is specific to your source file. Give him the test file since you're testing isn't indicative of his experience.

Each of the above will yield results that may inform you of the next step to take.
If both the re-encode and the new test file fail it would mean something on your end or his end may have changed whether software or firmware.


3) if you believe you've updated software you may want to regress to using the version used to encode the last file compatible with his playback device.

This would eliminate possible change on your end. You'd have to discuss with the client possible changes on his end or, otherwise, explore other options such as testing different software.

[Prathamesh Sathaye] "Digital Rapids is the only encoder we have at the lab."

3) You can download trials of Episode, Squeeze (or request a trial of Vantage) to see if another encoder with the same settings will yield different results.

This is all assuming that you are certain you've made no changes in the settings of your encoder you've been using to deliver to him previously.



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Prathamesh Sathaye
Re: First 90 secs of the video showing only black.
on Sep 6, 2015 at 1:33:56 pm
Last Edited By Prathamesh Sathaye on Sep 6, 2015 at 1:36:50 pm

Hi Craig,

Thanks for your suggestions.

I analyzed the file using bitrate viewer, it showed a VBR stream. Although i had selected CBR during transcoding.

I re-encoded using CBR+Filler mode, and the file is working properly at the client side.

BR.


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Craig Seeman
Re: First 90 secs of the video showing only black.
on Sep 6, 2015 at 3:03:07 pm

[Prathamesh Sathaye] "I re-encoded using CBR+Filler mode, and the file is working properly at the client side."

Hmm, So Digital Rapids CBR isn't CBR enough. Good that apps like Bitrate Viewer can reveal that.



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