Timeshifting with MDelay – Medialooks Help Center

With MDelay feature, you can make time shifting (a delay) for the required period for any sources.

It means that you can obtain video and audio with a delay between preview and real time. For example, you can see on a preview panel an event from live sources that have already happened earlier. Or start to download a network stream into a buffer and then playback it. You can use it for the following objects in MPlatform SDK - MFile, MLive, MMixer, and for any frames in MFormats SDK.

Main features of MDelay

Delaying the stream for a precise number of frames

Specify the desired delay and be sure that it is frame accurate at any moment.

Check the mdelay.time property description for details.

Adjustable compression quality

Set desired compression quality to get the balance between picture quality and CPU utilization with internal MJPEG encoder or uncompressed for a lossless result.

Check the mdelay.quality property description for details.

Possibility to use HDD or RAM to store of the delay buffer

Use RAM for fast access to the buffer or capture to HDD for a long period buffering.

Check the mdelay.buffer_duration property description for details.

Changing the video format on the fly

You can change the format of your live stream at any moment without having to reinitialize delay.

Possibility to append video to the existing delay buffer

Use a single buffer for the whole session and make cuts on the fly by stopping the delay process.

Check the mdelay.reset_on_open and mdelay.delete_on_close properties description for details.

Possibility to playback video from the delay buffer

Playback your buffer during the delay process, or after it's finalization and extract data whenever you need it. Just paly the *.sbe file like any other video file using MFile or MPlaylsit objects.

Check the mdelay.buffer_path property description for details.

Properties

Name	Default value	Description
mdelay.time	0.0	Delay duration. If a duration is greater than in buffer then the first frame will be shown until the delay time is not over. If the delay is 0 then you get real-time output.
mdelay.delete_on_close	false	Erase the delay buffer at the end of delay process flag. Possible values: "true" - the delay data will be erased from the buffer after closing the MDelay object. "false" - the delay data will be kept in the buffer after closing the MDelay object. Use this value if you need to keep the buffer for further playback and data extraction.
mdelay.reset_on_open	true	Reset the buffer on delay process start flag. Possible values: true - the old delay data will be erased from the buffer, so it will contain only the new one false - the old delay data will be kept in the buffer, so you'll be able to playback it. Use this value if you need to keep the buffered data for further playback and data extraction
mdelay.quality	80	Quality of video. Maximal value is 100, minimal is 1. If quality is 0 then you get uncompressed video. Dynamically changed value. The better the quality the more CPU and hard disk are used. If the video is uncompressed then CPU usage is minimal but hard disc should be fast and has enough free space(we recommend SSD for HD video).
mdelay.sync_time	120	Sets a time interval to force synchronization of delayed video
mdelay.split_progressive	true	This property is used for encoding optimization for progressive video (720p, 1080p). Possible values: true - each frame is divided into fields and each field is coded separately (like PSF) false - each frame is coded at once. Quality should be better but it requires more machine efficient.
mdelay.buffer_path	C:\MDelay\Live.sbe	A path to the buffer file. Please note that you can playback this file using just like any other file to extract the buffered data. In a case of capturing to HDD, the file will contain the full-size delay stream data. In a case of capture to RAM, it will have a 0 size but still can be played like any other file to extract the buffered data from RAM.
mdelay.buffer_duration	3600	Maximal time for buffering (in seconds). The more time then the more free space is required for buffering. It is possible to set 0 - in this case, RAM memory buffer will be used.
mdelay.buffer_size_mem	100M	Memory buffer size.
mdelay.static_deinterlace	true	Displays only one field of a static frame (e.g. a buffer is smaller than a position).
mdelay.static_mute	true	Mutes a static frame (e.g. a buffer is smaller than a position).
mdelay.video_codec	mjpeg	Video codec in use for buffering
mdelay.video_props	b='5M'	Video codec properties (GOP size, buffsize, etc.)
mdelay.min_disk_space	10M	A limit of free disk space to keep the buffering. Once there is not enough space, MDelay returns an error.

All these parameters you can change with the PropsSet method or in the system registry:

HKEY_CURRENT_USER\SOFTWARE\Medialooks\MPlatform\MDelay

MDelay with MPlatform SDK

You should enable MDelay with PropsSet method like:

(mySource as IMProps).PropsSet("object::mdelay.enabled", "true");

The same approach is used to configure any MDelay-related properties. For example, to specify delay duration to 10 seconds you should call:

(mySource as IMProps).PropsSet("object::mdelay.time", "10");

Note please that receiver objects (MPreview, MRenderer or MWriter) do not support MDelay feature because they receive frames from source objects.

MDelay with MFormats SDK

You should create an instance of MDelay object

MDelayClass myDelayPlugin = new MDelayClass();

Then configure parameters of delaying with the PropsSet method for the myDelayPlugin object. Note please that in MFormats SDK you don't need to specify mdelay.enabled property for your source object because you work with the plugin separately and there is no dependency on where the frames are from.

For example, to set a duration of delay to 10 seconds you should call:

myDelayPlugin.PropsSet("mdelay.time", "10");

When the object is configured you can use it to make a delay:

int framesRest;
MFFrame modifiedFrame;
((IMFProcess)myDelayPlugin).ProcessFrame(sourceFrame, out modifiedFrame, out framesRest, "");

Then you can use the modified frame according to your requirements. For example, show it on preview:

((IMFReceiver)myPreview).ReceiverFramePut(modifiedFrame, -1, "");

VANC Timecode delay

To delay a timecode for devices you should make several settings:

For MLive or MFLive object:
set "vanc.capture" property to "1" with PropsSet method;
set required lines with "vanc.lines" property (for example, vanc.lines=20, 21). If this property is empty or "all" then all lines are copied.
For MRenderer or MFRenderer object:
set output.10bit = true
If it is required you can enable to copy VANC data from frame or disable it:
output.copy_vanc = 0 - don't use
output.copy_vanc = 1 - copy VANC first then add CC
output.copy_vanc = 2 - add CC first and then copy VANC

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