Tech Tips - PowerPoint to MPEG Conversion

Overview

MPEGRepairHD can be used to convert any PowerPoint presentation to an MPEG stream with a user selectable slide duration.

Demo of PowerPoint Conversion

A demonstration of the PowerPoint conversion process can be obtained by clicking ppt2mpeg.zip. Download this file, unzip the directory structure and execute the runppt.bat file.  The demo compresses a sample PowerPoint slide sequence into an MPEG file using the batch process of MPEGRepairHD. The resultant PixelTools.Mpg can be viewed on any MPEG-2 player.

PowerPoint to MPEG using the MPEGRepairHD GUI

MPEGRepairHD can encode a sequence of bitmaps of encoding example
any dimension with patent-pending technique that
instructs MPEG decoders to display each
bitmap with a specific duration. Click on image to see actual size screen.

The first step is to convert your PowerPoint presentation into a sequence of bitmap files.  Select Edit | Select All to select your entire presentation. The select File | Save As | Device Independent Bitmaps and enter the name of the
first bitmap to be saved in the Save As dialog box.

The next step is to configure MPEGRepairHD to encode the sequence with the appropriate duration.  An easy way to do this is to use the PptToMpg.ini in the above referenced demo.  Just depress the down arrow in the Base Encoding Profile edit box, select the Load Custom ini file and browse to the PptToMpg.ini configuration file.  Browse to the first slide using the File button in the Encode Input edit box.  Browse or enter the name of the resultant MPEG file in Encode Output edit box.  Depress the Run button to complete the process.

The trick in creating high quality MPEG streams is using the correct parameters. The parameters require some non-intuitive selections. Some tips on Optimize Encode | Configure parameter selection:

Number of Frames: Select the total number of source slides that you wish to convert into an MPEG file. You can also enter ALL which will encode all slides in the sequence in your source directory.

Bitrate: Select the desired output bit-rate for your target decoder.

Parameters -
Output Rate:Select: the Output Frame Rate appropriate for your target decoder. 25, 29.97 or 30 are typical frame rates.  Do not use the frame rates in parenthesis as these are not legal MPEG rates.

Compressed Image Size: Enter the dimensions of your bitmap slides

Enable Stuffing: Check this option to create constant bit-rate streams. For variable bit-rate decoders, un-checking this option will create extremely small high quality MPEG files

M: Must be 1 for this mode

Input Control: Select the Multiply Input Frame Rate By: option and enter your desired frame rate multiplier in the adjacent edit box to result in your desired slide duration.  For example, if your frame rate has been set to 30 (frames per second) and you want each slide to be displayed for 5 seconds, the multiplier should be 30 x 5 or 150.

Audio /Mux: If you wish to create a multiplexed stream including an audio file, check the appropriate Output Stream and Audio Source Options.  Depress the Mux button to select your desired multiplexing type and output bit-rate.

PowerPoint to MPEG using the Expert Workshop® SDK

The Expert Workshop SDK can be used to encode a sequence of bitmaps to be displayed at a slow duration IE several seconds per slide.

Some hints at setting parameters:

VidEncodeParams_struc .frame_rate_code should be set the actual output frame rate code that your target decoder runs at in the

VidEncodeParams_struc .M should be set to 1

VidEncodeParams_struc .eNABLESTUFFING should be set true to create constant bit-rate streams or false for highly compressed variable bit-rate streams.

VidEncodeInputControl_struc.RateBy should be set to the number of repeated frames you wish to add to each source bit-map. For example, if your frame rate has been set to 30 (frames per second) and you want each slide to be displayed for 5 seconds, the RateBy value should be 30 x 5 or 150.

To create the MPEG file, call ExpEncodeNextFrame for the number of source slides. The encoder will add flags that instruct the decoder to repeat the current frame for the number of RateBy frames.

Specification

Any bitmap file sequence (that has a horizontal size evenly divisible by 16) created from a Microsoft PowerPoint presentation can be converted to an MPEG file.

The PixelTools encoder can add null frames as specified in the Input Control | Multiply Input Frame Rate By value.  This will create a legal MPEG stream whereby the decoder will be instructed to display each bitmap for an extended length of time.

Disabling the Parameters | Enable Stuffing button will create an amazingly small MPEG file that is mostly a function of the compressed sizes of the source bit-maps and not the actual length of the stream.

 

 

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