Tag Archives: ffmpeg

Compiling WebM into FFMpeg for Windows

I have updated this post with a newer version of the VP8 patches to FFMpeg and support for libvorbis instead of the built in vorbis support.

Google has released source for the VP8 codec as the WebM project. The WebM project will be an open alternative in the HTML5 video tag codec space and being backed by Google, who will use it for YouTube, will give it a fighting chance. WebM is starting to be integrated into FFMpeg but there are still some patches that need to be applied. While there are some guides to how to build FFMpeg for Linux with VP8 WebM support I wanted to get it compiled for Windows.

First off this won't be done using a Windows install but instead using Virtual Box with a fresh install of Ubuntu 10.04 desktop. It is just faster and easier that way. So go ahead and grab Virtual Box and get Ubuntu installed on it before you continue.

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How to Create iPad Formatted Videos Using HandBrake or FFMpeg

This is for those who may want to load a video onto their iPad with iTunes that isn't in the correct format. I needed to do this because I was trying to put an iTunes University video on my iPad a couple days ago and iTunes complained that it wasn't in the correct format for the iPad. I'm not sure exactly how that could be but I decided to take the opportunity to see if I could use HandBrake to easily convert it to an iPad friendly format. There is currently no pre-loaded iPad configuration for HandBrake like there is for the iPhone and iPod Touch so I created a few profiles that can easily be imported into HandBrake to output different sizes for the iPad:

Note that when you import videos using iTunes the iPad puts them in their own Videos app unlike the iPhone where they show up under the iPod app. You will want to find the Videos icon if you don't already know where it is:

iPad Videos Screenshot

After verifying that the above 4×3 version worked for the iTunes University video I went about testing it on a couple other video formats. I tested the Big Buck Bunny video that I also used for my post on iPad video streaming in both 640×360 and 1024×576 output formats. Both resolutions looked great. I also tried converting a DVD. If you decide to convert a DVD you will probably want to turn on de-interlacing in HandBrake. You do that by first selecting the "Picture Settings" option:

HandBrake Picture Settings Screenshot

Then the filters tab and then select the type of de-interlace you want (fast, slow, slowest):

HandBrake DeInterlace Settings Screenshot

If you want to use FFMpeg to do all this you can. The following is a slightly modified version of the streaming command I'm using that will output a high bitrate version of the input video:

ffmpeg -y -i input.avi -acodec aac -ar 48000 -ab 128k -ac 2 -s 1024x768 -vcodec libx264 -b 1200k -flags +loop+mv4 -cmp 256 -partitions +parti4x4+partp8x8+partb8x8 -subq 7 -trellis 1 -refs 5 -coder 0 -me_range 16 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -bt 1200k -maxrate 1200k -bufsize 1200k -rc_eq 'blurCplx^(1-qComp)' -qcomp 0.6 -qmin 10 -qmax 51 -qdiff 4 -level 30 -aspect 16:9 -r 30 -g 90 -async 2 output.mp4

iPhone HTTP Streaming with FFMpeg and an Open Source Segmenter

With the release of the iPhone OS 3 update came the ability to do live streaming. There are a few types of streaming and each requires a certain encoding and segmentation. I've put together a cheat sheet on how I went about building a static stream using FFMpeg and an example segmenter that someone has posted. I'm not covering windowed streams in this post but if you are thinking about implementing a windowed stream the following will help you make a step in that direction.

Before getting started it is best to read over the Apple documentation on HTTP live streaming. Start out with the iPhone streaming media overview. This document covers the basics of how the streaming works and has some nice diagrams.

If you want even more information after reading the overview you can take a look at the HTTP Live streaming draft proposal that was submitted to the IETF by Apple. It covers the streaming protocol in complete detail and has examples of the stream file format for reference.

Once you are ready to start grab a decent quality video clip to use. If you don't have one handy I found a nice list of downloadable HD clips in various formats for testing.

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