Page 1 of 1: Digital TV to DivX conversion guide

How To Reduce A Film You Recorded Off Digital TV Down From 3GB To A 700MB CD

Background

I came across a Hauppauge DVB TV card and managed to get the buggy little thing to work. I was a little disappointed the massive video sizes though so I searched the web for tools to solve the problem. When I could not find any I set about trying to record from my TV card, only to be thwarted from the outset. So I was left with the option of re-encoding the mpeg streams that the Hauppauge program delivered. This I managed. If you are in the same boat then here is how.

Introduction

I use Gordian Knot since all the tools are contained in a single install.

If you are familiar with DVD ripping then all I need tell you is that you need to use VStrip to decode the mpeg stream, making sure that Is Vob? is disabled.

For the rest of you here is a step by step guide. This guide is a little long but it is laid out in plain English so you should have no problems whatsoever.

How To

1)     Create a project file.
At the bottom right of Gordian Knot select an entry from the drop down list, click rename and type the name for the project such as TV or Film.

2)    Decrypt the mpeg file.

a.      Open VStrip by clicking the VStrip button on the Ripping tab.

b.     On the input tab click add, select filetype *.* and then open your mpeg file.

c.      Uncheck Is Vob?

d.     On the output tab click the ‘…’ button and create a file.

e.      Click the Run button at the bottom left of VStrip.

f.       If your video is split up into more than one file:

                                                              i.      Open the next file (according to the numbers in the file names).

                                                            ii.      Check Append on the output tab.

                                                          iii.      Click Run.

                                                          iv.      Repeat for all mpeg files.

g.      Close Vstrip.

3)    Demux the vob file.

a.      Click the DVD2AVI button.

                                                              i.      Open the vob file

                                                            ii.      Select option>preview. A Statistics window appears. You can stop this after a few seconds by selecting File>Stop. We do need this information but for me watching Digital Video Broadcasts in the UK the video is always Interlaced, PAL, 25fps and either 4:3 or widescreen. The Audio is always MPEG Audio.

                                                          iii.      Click File>Save Project and select a name.

                                                          iv.      Close DVD2AVI.

4)    Set the settings.

a.      Click the Open button at the bottom left of Gordian Knot and select the d2v file you just created with DVD2AVI.

                                                             i.      Bitrate.

1.      Video.

a.      Back in Gordian Knot, click on the Bitrate tab and on the right, choose the codec you want to use.

b.     The reasons you are doing this re-encoding is to make your videos smaller. Either so it fits on a CD or so it does not take up ridiculous amounts of HD space.

                                                                                                                                      i.      For CD
If you want to fit a video onto a CD(s) then check the calaculate average bitrate radio button and select the size of the CD(s) from the drop down box over on the right and also the number of CDs. (About 1 CD per hour for almost lossless re-encoding.)

                                                                                                                                    ii.      For HD
If you just want to make the file smaller then I recommend that you do not restrict yourself to a file size but set the bitrate instead. Click Calculate Avi File Size and at the middle right type a bitrate value. About 2 000 produces lossless re-encoding.

2.     Audio.

a.      Set the audio bitrate by selecting one from the drop down box at the middle left (Audio A). 320 is reasonably lossless whereas 96 will do fine for news broadcasts.

b.     Select 1x vbr-mp3 in the interleaving section to have the audio interleaved with the video back into a single file.

                                                           ii.      Resolution.

1.      Click the Resolution tab.

a.      Select the Input Pixel Aspect Ratio that corresponds with the statistics you saw in DVD2AVI.

b.     Crop.
Most TV signals have black borders which you can keep but the sharp border between the black areas and the picture will take up a couple of MB so if you are space conscious it is best to crop it off but try to keep as much of the picture as possible.

                                                                                                                                      i.      Click the Pixel radio button.

                                                                                                                                    ii.      On the video viewer press play and while the video is playing use the four number fields in the Crop section of Gordian Knot to crop pixels from the edges.

                                                                                                                                  iii.      Click Stop on the viewer.

                                                                                                                                  iv.      Click Smart Crop All in Gordian Knot, which may take off a few more pixels in order to keep the original aspect ratio.

                                                                                                                                    v.      You can take a look at the result of both the cropping and the resolution change by clicking view>resized in the video viewer.

2.     The trade off between resolution and Bits/(Pixel*Frame).

a.      For your video not to look bad you want the slider as far to the right, giving a higher percentage of the original resolution. If you are trying to fit an hour onto one CD then you need to keep the Bits/(Pixel*Frame) value down towards 0.30. If you are trying to fit 2 hours onto one CD then you need to keep the Bits/(Pixel*Frame) value down towards 0.20. If you are re-encoding to your HD then this need not be an issue.

b.     If you are finding this difficult then the only solution is to increase the file size. If you do not want to do that then just encode and your video will be a little less sharp than the original.

                                                                                                                                      i.      For those of you working towards a CD(s) this means adding an extra CD.

                                                                                                                                    ii.      If you have specified a bitrate, you need to increase it, which will have a knock on effect to the file size.

5)    Encode.

a.      Pass 1.

                                                              i.      In the viewer click Save & Encode.

                                                            ii.      Select fast de-interlace on the left if DVD2AVI told you that your mpeg was interlaced.

                                                          iii.      Select a resize filter: Bilinear is the best/slowest and Simple is the fastest.

                                                          iv.      At the bottom right there is a Compressibility Check. This is the first pass.

                                                            v.      Select Use and click Now.

                                                          vi.      Click OK.

b.     Revise.

                                                              i.      The statistics from the compressibility test have been loaded into Gordian Knot in the centre at the bottom. Before you were guessing how much you could compress the file but now Gordian Knot knows its compressibility. For better results reduce the resolution, by moving the slider to the left, until the percentage passes above 60%. Don’t be afraid of reducing the resolution otherwise the video may be blocky. Again if you have overkilled with a massive file size then this will not be an issue for you.

c.     Pass 2.

                                                              i.      Click Save & Encode.

1.      Select fast de-interlace on the left if DVD2AVI told you that your mpeg was interlaced.

2.      Select a resize filter: Bilinear is the best/slowest and Simple is the fastest.

                                                            ii.      Click Save & Encode.

                                                          iii.      Create a file.

                                                          iv.      The correct pro features should be enabled in the tab of the video codec you are going to use.

                                                            v.      Click the Audio 1 tab.

1.      Click the select button and then select the mpeg audio mpa file that was demuxed earlier by DVD2AVI. This enables the MP3 button and the Finally Mux checkbox.

2.      Keep the Beesweet encoder checked as we need Beesweet to open the mpeg audio file.

3.      Set the bitrate that you specified earlier.

                                                          vi.      Click the appropriate video codec tab again.

                                                        vii.      Click the Add Job to Encoding Queue and click Yes.

The End