Some hints and thoughts about import of ffmpeg created AVI video files into IADS using IrigTime tag
Ruben
The playback client's video player has an awesome feature, that instead of having to declare a video file and its corresponding IrigStartTime, one is able to just "select" a video channel by providing IADS with a properly named avi file (VideoChannelXX.AVI).
Furthermore, if the AVI-file start time is present within AVI's RIFF header metadata field "STRN" (e.g. IrigTime=123:21:00:00.000 ), the file start time will be set to the correct value automatically
Since we create our 3rd party video files with ffmpeg (e.g. when coming from an external source such as grabbed Hi8 tapes), which doesn't provide for editing the RIFF header’s “STRN” field (AFAIK), I asked Symvionics whether it would be viable that IADS Client's video player supported the comment field "ICMT" for Irig start time just as the “STRN”-field is used. Symvionics answered me, that they try to get this done for the next release.
-------------
Furthermore, I had performance issues when playing back several videos at once. The videos themselves were jerky and without sound for some 10-20 seconds after starting or spooling. Spooling/ sliding the video time line proved notchy/jerky, too, and resulted in few frame updates within the video player display while spooling.
The following steps helped me:
- Having the video window on the main screen (which has full Directx hardware acceleration, both in Win7 and XP)
- using AVI files with MPEG2PS Codec instead of h.264 (which is usual for newer and better MP4 container, however I can’t use MP4 due to compatibility reasons with other used software)
- using FFMPEG’s mpeg2video’s standard group of pictures (GOP) (no B-frames, GOP size=12)
The steps mentioned resulted in a decent video player behavior with instant smooth playback and with fast spooling and recovery after spooling/ stopping and starting the video
Here are some other video player related information that might help other users:
>- By the way, is the video player of IADS
able to rotate the videos
>"online" (so we wouldn't have FFMPEG letting do it)?
In Iads version 9.1 (due out around October), the Iads video player display
will have the ability to rotate the video 0 to 359 degrees. This should work
for you.
>Do You know whether IADS is using the PTS clock for synchronization for
>containers MPEG2-TS (.m2t files) and MPEG2-PS (.mpg files) (that are
>playable in IADS), too ? Or is it "just start time sync" for
those two file
>types as it is according to Your writing for AVI files?
For all containers, it uses a combination of PTS clocks (when available in
containers such as TS) as well as the start time. It simply takes the
internal clock of whatever mechanism and 'offsets' it by the Irig start time
in the file. Think of it this way, each container has it's own notion of
time. We simply use that time notion and offset it by the Irig start time.
Streaming is always 'easier' than random access or scrolling. You simply
decode the frames in the order that they appear, then you use the PTS to
schedule their display. I'll bet that the TS files don't 'scroll back and
forth' very well. This is where the TS format is inferior to other
containers such as .MPG, .MP4, or .AVI.... and this is why Iads prefers
these formats for the end user. It gives them the ability to slide the data
and video back and forth in a smooth, accurate, and synchronized manner. TS
files are a 'linear-forward' format and the other containers are built for
random access.
James Bretz
The playback client's video player has an awesome feature, that instead of having to declare a video file and its corresponding IrigStartTime, one is able to just "select" a video channel by providing IADS with a properly named avi file (VideoChannelXX.AVI).
Furthermore, if the AVI-file start time is present within AVI's RIFF header metadata field "STRN" (e.g. IrigTime=123:21:00:00.000 ), the file start time will be set to the correct value automatically
Since we create our 3rd party video files with ffmpeg (e.g. when coming from an external source such as grabbed Hi8 tapes), which doesn't provide for editing the RIFF header’s “STRN” field (AFAIK), I asked Symvionics whether it would be viable that IADS Client's video player supported the comment field "ICMT" for Irig start time just as the “STRN”-field is used. Symvionics answered me, that they try to get this done for the next release.
-------------
Furthermore, I had performance issues when playing back several videos at once. The videos themselves were jerky and without sound for some 10-20 seconds after starting or spooling. Spooling/ sliding the video time line proved notchy/jerky, too, and resulted in few frame updates within the video player display while spooling.
The following steps helped me:
<!--[if !supportLists]-->- <!--[endif]-->Having the video window on the main screen (which has full Directx hardware acceleration, both in Win7 and XP)
<!--[if !supportLists]-->- <!--[endif]-->using AVI files with MPEG2PS Codec instead of h.264 (which is usual for newer and better MP4 container, however I can’t use MP4 due to compatibility reasons with other used software)
<!--[if !supportLists]-->- <!--[endif]-->using FFMPEG’s mpeg2video’s standard group of pictures (GOP) (no B-frames, GOP size=12)
You received this message because you are subscribed to the Google Groups "IADS" group.
To unsubscribe from this group and stop receiving emails from it, send an email to iads+uns...@googlegroups.com.
To post to this group, send email to ia...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/iads/181bfa77-8a4d-479d-96f9-ec64a40ed79c%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
Ruben
Dear James, Dear Symvionics and users,
But I found a general issue (for both IrigTime fields: RIFF's STRN/ AVI's ICMT):
This implementation leads to the following unwanted behavior (when using procedure 1. or 2.):
I mean, if one absolutely wants this field to be taken from pfConfig's values, one could delete the value in the AVI file or maybe You could add a new property to VideoPlayer's property bag e.g. "StartTimeSource": "File" or "pfConfig"
Many thanks for taking care of this. If someone has a different suggestion, please don't hesitate...
Best regards,
James Bretz
You received this message because you are subscribed to the Google Groups "IADS" group.
To unsubscribe from this group and stop receiving emails from it, send an email to iads+uns...@googlegroups.com.
To post to this group, send email to ia...@googlegroups.com.
Ruben
thanks for the hint that "the player should default to the embedded ICMT/STRN setting" if no entry is in the pfConfig file. Even though obvious, it didn't come to mind.
Deleting the IrigStartTime entries in pfConfig by far beats the error prone hassle of setting VideoPlayer's property bag items back and forth for each video.
Problem solved! Thanks again, Ruben.
James Bretz
You received this message because you are subscribed to the Google Groups "IADS" group.
To unsubscribe from this group and stop receiving emails from it, send an email to iads+uns...@googlegroups.com.
To post to this group, send email to ia...@googlegroups.com.