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The notes below are mainly directed at our partners but are of use to those wishing to learn encoding for themselves if they have video they want to load onto a website.


Encoding video using Windows Media Encoder.

January 2004.

What is encoding?

Video files are very large and need to be compressed before they are put on the Internet. This compression process is called encoding. The level of compression depends on the speed of the connection that the potential viewer is using: lower speed connections need more compression.

Encoding Instructions:

Currently Southwark.tv is using Media Encoder 9 producing files designed to be seen in Windows Media Player 9. This is worth remembering, because much time is currently spent encoding video so that it can be read by earlier versions of Media Player such as 7. If Media Player 9 becomes more common and Media Player 7 is outdated and obsolete, some of what follows won’t apply. If you are loading and using Encoder for the first time some screens may have a slightly different appearance to the one I describe here.

When one opens Media Encoder 9 a box entitled ‘New Session’ opens up with 2 tabs: wizards or quick start. The open tab is wizards; if you are not on wizards click on that tab. There are 5 options: “Custom Session”, “Broadcast Live Event”, “Capture Audio or Video”, “Convert a File” and “Capture screen”. We use ‘custom’, because we want to create our own screen size and make the file readable by someone with Media Player 7. If we were just doing a straight encoding session we could use the “Convert File” option, but for this purpose we are using the “Custom Session” option. Click on that option and the ‘New Session’ box closes.

Within the Media Encoder interface a new box opens, “Session Properties”, with a number of tabs across the top. Reading from the left we have “Sources”, “Output”, “Compression”, “Video Size”, and several others which are irrelevant to us. The “sources” tab will be open when you first enter the box. In the middle of the screen it says ‘source from’ with boxes for ‘devices’, ‘file’ and ‘devices and file’. We usually use files that are saved onto the computer so if you have your video already on your computer click the ‘file’ box, which will be highlighted by the green dot. If you are working directly from a camera click on the devices box; the camera will need to be on so that the computer can interface with it.

Once you have clicked on ‘file’ the options immediately below change to ‘file name’ with a ‘browse’ box to the right. Click on browse, find the file that you want to encode, and make sure it is displayed in the ‘file name’ box’. You are now finished with this tab; click onto the next tab ‘output’.

There are 3 options on this tab: ‘push to server’, ‘pull from encoder’ and ‘archive to file’, with the ‘pull from encoder’ option probably containing a green tick. At Southwark.tv we create a file that we subsequently send up to the server, so we want the ‘archive to file’ option. Click on this, and the ‘archive to file’ box is now called ‘Encode to file’. We need to give the encoded file a different name to the original, remembering that we are going to create 2 encoded files, one for broadband, the other for dial-up modems. Use a file naming system that you will understand; as a suggestion, we tag _lrg and _sml after the original filenames to differentiate them. For example, if our original file was called ‘myvideo’, I would call the broadband version ‘myvideo_lrg’, and the dial-up modem version ‘myvideo_sml’. Adopt a naming system you understand, and ensure you give the files a different name from the original. I would suggest using the ‘browse’ button to find the path and name of the original file, then add the appropriate suffix (whether _lrg or _sml or whatever you decide) then save the file. You can keep the encoded files in the same folder as your original for convenience. Windows will automatically add the file type .wmv; Southwark.tv video files need to be .wmv files. Ignore the rest of the tab and click on the next tab ‘compression’.

File Compression for Broadband:

This is the tricky one. You will see four options: ‘destination’, ‘video’, ‘audio’ and ‘bit rates’. You don’t need to touch the video or audio options; just make sure they say ‘multiple bit rates’, even though we will in fact be only putting in single bit rates. The bottom box has various bit rates in the left column, a frame rate in the middle and an output size in the right column. For broadband users we have been using 282kbps or 340kbps; these aren’t at the high end, but are good enough for most users. The frame rate for broadband is 25fps (frames per second), which is also the standard frame rate for the PAL system we use in the UK. You will notice the output size says 384x288; for Southwark.tv we use an image size of 320x240, and we will be changing to that size in the next tab. One of the bit rates will be highlighted; unclick whichever is highlighted and click on 282kbps to make a broadband file. It’s essential to make sure that only one bit rate is highlighted in green, because our admin. site does not allow multiple bit rate options. Assuming you have highlighted 282kbps, look at the top box ‘destination’ again. You will see to the right of it an ‘edit’ button. Click on this; a box opens called ‘custom encoding settings’ with two tabs, ‘general’ and ‘282kbps’. The ‘general’ tab will be open and you will see in the middle of the screen in blue type ‘media types’; both audio and video have green checkmarks to the left, and 2 dropdown boxes to the right called ‘mode’ and ‘codec’. Open the ‘codec’ box dropdown menu under video (you only need to change the video codec, not the audio) and choose ‘Windows Media Video V7’. This means that the file can be read by a computer with Media Player 7; if you don’t choose this option someone with an earlier version of Media player than 9 will not be able to see your video. Now click on the 282kbps tab at the top of the box.

At the top it says ‘audio format’. Generally speaking, leave this alone unless you want to change the balance between audio and video. Beneath this change the video size to 320x240, and for the buffer size either click the ‘use default’ box or enter 5 seconds, and ignore the rest of the options. If you hit the ok button at this point you are taken to ‘session properties’ box which summaries your chosen settings. The details, for a broadband file, should read something like

Audio encoding mode: CBR
Video encoding mode: CBR

Audience: 282 Kbps
Audio codec: Windows Media Audio 9
Audio format: 32 kbps, 32 kHz, stereo CBR
Video codec: Windows Media Video V7
Video bit rate: 241 Kbps
Video size: 320 x 240
Frame rate: 25 fps
Key frame: 8 s
Image quality: 60
Buffer size: 5s Audio encoding mode: CBR

At this point if the settings look correct hit the ‘Apply’ button below. If they need amending hit the ‘edit’ button next to ‘destination’ and retrace your steps until you find the item you want to change and then hit apply. These are all the tabs you need to access. You are now back at the encoder screen and ready to encode; to the right of the screen there is a black input box. Above the session properties box there is a white arrow on a green background that says ‘Start Encoding’. Click on this arrow to start the encoding session.

As you are encoding:

The session properties box will disappear and you will have two boxes in the middle of the screen; one saying ‘input’, the other ‘output’. Input is your original file; output shows the compressed file you are creating. From the output box you will get some idea of how your work will look to the internet viewer. You will notice that you don’t hear any audio as the file encodes, but to the left of the input screen there are audio levels bars. The programme automatically stops when it reaches the end of the file and a dialogue box appears with useful information about file sizes, etc. On the right of the box there is an option ‘Play Output file’ which you may want to use if you are still learning or unsure that the process is working. When you are happy hit the ‘Close’ option and you are back to the Encoder screen. The last thing to do is save your session. You already have your encoded file; this option simply lets you save the settings for this session. It is not necessary to do this if you don’t want to. If you want to save the session, give it a name and windows will automatically append the .wme file type.

We have now created the broadband file.

Creating the dial-up modem file:

For simplicity’s sake I have pasted the instructions above with the relevant changes.

When one opens Media Encoder 9 a box entitled ‘New Session’ opens up with 2 tabs: wizards or quick start. The open tab is wizards; if you are not on wizards click on that tab. There are 5 options: “Custom Session”, “Broadcast Live Event”, “Capture Audio or Video”, “Convert a File” and “Capture screen”. Open the ‘custom’ option’ and the ‘New Session’ box closes.

Within the Media Encoder interface a new box opens, “Session Properties”, with a number of tabs across the top. Reading from the left we have “Sources”, “Output”, “Compression”, “Video Size”, and several others which are irrelevant to us. The “sources” tab will be open when you first enter the box. In the middle of the screen it says ‘source from’ with boxes for ‘devices’, ‘file’ and ‘devices and file’. Once you have clicked on ‘file’ the options immediately below change to ‘file name’ with a ‘browse’ box to the right. Click on browse, find the file that you want to encode, and make sure it is displayed in the ‘file name’ box’. You are now finished with this tab; click onto the next tab ‘output’.

There are 3 options on this tab: ‘push to server’, ‘pull from encoder’ and ‘archive to file’, with the ‘pull from encoder’ option probably containing a green tick. Click on the ‘archive to file’ option; the ‘archive to file’ box is now called ‘Encode to file’. We need to give the encoded file a different name to the original (use the _sml suffix as suggested above if you wish). I would suggest using the ‘browse’ button to find the path and name of the original file, then add the appropriate suffix and save the file. Ignore the rest of the tab and click on the next tab ‘compression’.

At this tab simply unclick any chosen bit rate and choose the 58kbps option which you can find by scrolling down. Dial-up modems can process 56kbps, so this is close enough. Any speed lower than that and you might as well not bother. Notice that at 58 kbps you only have 12.5 frames per second (it’s a slower connection speed so there is worse picture quality). The default image size shows as 192x144; go into the ‘58kbps’ tab and change that to 160x120, the size chosen for the Southwark.tv admin. site. Remember to make the other codec changes outlined above. Once you have hit the ‘apply’ button your session properties should look something like this:

Audio encoding mode: CBR
Video encoding mode: CBR

Audience: 58 Kbps
Audio codec: Windows Media Audio 9
Audio format: 12 kbps, 8 kHz, stereo CBR
Video codec: Windows Media Video V7
Video bit rate: 40 Kbps
Video size: 160 x 120
Frame rate: 12.5 fps
Key frame: 10 s
Image quality: 50
Buffer size: 5 s

At this point if the settings look correct hit the ‘Apply’ button below. If they need amending hit the ‘edit’ button next to ‘destination’ and retrace your steps until you find the item you want to change and then hit apply. These are all the tabs you need to access. You are now back at the encoder screen and ready to encode; to the right of the screen there is a black input box. Above the session properties box there is a white arrow on a green background that says ‘Start Encoding’. Click on this arrow to start the encoding session.
You will notice a heavy loss of quality; this is inevitable. Save the session properties if you wish and you should have 2 files ready to upload to the Southwark.tv site.