Most Linux video encoding and streaming tools are free, and they are easy to set up. In less than an hour, one could have a streaming server serving a dozen of MPEG-4 clips. MPEG-4 allows encoding to happen at different bit rates and resolutions, while these are limited in some other codecs. The utmost advantage of using MPEG-4, of course, is it offers a standard format that is becoming more popular. Unlike proprietary formats, MPEG-4 is an open standard, so adding MPEG-4 support is easy. A few MPEG-4 audio and video players already are on the market, and more of them will be released in the future.

About the Setup

If you are streaming MPEG-4 clips, the setup is simple. You need only an MPEG-4 streaming server with a fast connection. A DSL line would be enough if you are serving only a few buddies. If you want to implement video conferencing or surveillance systems, though, you need a live MPEG-4 encoder and a compatible video capturing device under Linux. Of course, boards are on the market that encode video to MPEG-4 on-fly, but they are generally quite expensive for home users. Under Linux, the MPEG4IP suite, the FFmpeg multimedia system and Apple's Darwin Streaming Server offer an inexpensive way to stream and create MPEG-4 content.
Compiling and Installing MPEG4IP

The MPEG4IP project began in summer 2000 by David Mackie, who works on multimedia streaming for Cisco Systems. He is no longer active on the project and Bill May is now the main developer. The project is licensed under Mozilla Public License 1.1, but the codecs used in MPEG4IP are subject to patent royalties depending on how they are used. You should read the COPYING file in the package before using them. Licensing fees also are associated with MPEG-4, including a per-stream charge. People who plan to go commercial should check it out first.

In the MPEG4IP box are handy tools that can help you encode and play MPEG-4 clips. You may get your copy from mpeg4ip.sourceforge.net/ or from its CVS on SourceForge. While I was writing this article, 0.9.7 was the latest stable release. If you would like to try out new features, get release 0.9.7.7 from the CVS repository. You also need the LAME package if you are compiling mp4live (enabled by default), the live MPEG-4 encoder for live broadcasting. Extract the package and begin compiling:

tar zxvf mpeg4ip-0.9.7.tar.gz
./bootstrap
make
make install

To compile without mp4live (and LAME) add --disable-mp4live after ./bootstrap. MPEG4IP uses a modified version of the SDL library, so you do not need to bother installing it. You do need the GTK+ library, though, if you want to compile the GUI player.
Compiling and Installing FFmpeg

The FFmpeg Multimedia System itself is a complete solution for creating and streaming MPEG-4. When this article was written, the stable release was 0.4.6. The streaming server supports only HTTP streaming at this stage, so we take advantage of FFmpeg, the encoder, at the moment. Get the source from SourceForge and begin compilation:

tar zxvf ffmpeg-0.4.6.tar.gz
./configure
make
make install

This configuration is sufficient for encoding MPEG-4 video. If you want MP3 and OggVorbis encoding support, add --enable-mp3lame and --enable-vorbis and install their respective libraries beforehand.
Extracting Content from the Source

Here at my school video clips are stored in different formats. This is likely to be the case in most situations--you do not need to convert only one format to MPEG-4 but many formats. Some of my fellow video team members store the clips in MPEG-1 and 2, some of them in DivX or XviD AVI and some use DV AVI if they do not have time to encode. Here, we discuss how we encode these formats to MPEG-4, as they are likely to be the most common formats we might come across.

No single tool with a single button can do all the encoding work well for you. You need to encode the video and audio separately, so the first thing to do is split up the video and audio. Under Linux, FFmpeg is a Swiss knife for video processing. It encodes and decodes various video formats and supports some basic video processing, such as de-interlacing. To extract the audio track from the source, type:

ffmpeg -i -vn

The command can be applied to both DV/DivX/XviD AVI and MPEG files. The vn switch disables video in the output file. The resulting file would be a raw PCM audio file.
Encoding the Audio

To generate an MPEG-4 complaint clip, you need MPEG-4 AAC audio. The MPEG4IP suite includes a redistributed AAC encoder called FAAC. At the of this writing, FAAD2 is available on SourceForge and uses the version 1.1 library for encoding, which is a bit faster. If you are interested, you can grab the source from faac.sourceforge.net. A copy of the FAAC binary should have been installed properly when you were installing the MPEG4IP suite.

To encode the raw PCM audio track split by FFmpeg, type:

faac -m4 -b64 -r48000 -pLC

The -m flag specifies the AAC MPEG version. We are creating MPEG-4 AAC so we use -m4. The -b flag specifies the bit rate for the encoded output. A value of 32 or 64 produces satisfactory quality and is an economical size for streaming. The -r flag specifies the sampling rate of the input file; otherwise, FAAC would not read the file. Instead, it would produce an error notifying the user that the file format is not supported. The last -p flag, which specifies the profile, is a bit more complicated. The Main profile includes all the coding tools (an MPEG term understood as "features"). The LC profile, which stands for low complexity, reduces decoding complexity on the client side (for slow devices or machines). The LTP profile, which stands for long term prediction, provides significant improvement in quality but also increases decoding complexity. It is best used for audio tracks with clear pitch. I use LC most of the time for my school's MPEG-4 clips.
Encoding the Video

MPEG4IP suite comes with two encoders, mp4encode and xvidenc. mp4encode encodes an AVI file to an MPEG-4 video clip with its built-in OpenDivX encoder or ISO MPEG-4 encoder, if specified. xvidenc, on the other hand, encodes raw video file with the XviD encoder. If you encode with these utilities, the input AVI file must contain a video track in raw YV12 (YUV12) format, and the audio track must be in raw PCM format. In this article, instead, I show how we can use FFmpeg to simplify the video encoding process. Because FFmpeg decodes DV, MPEG-1 and 2, DivX and XviD, we can skip the step of preparing YV12 raw for mp4encode or xvidenc. The command for encoding from these formats to ISO MPEG-4 video is the same:

ffmpeg -i -an -b 300 -vcodec mpeg4

FFmpeg then encodes the input file without audio (the -an flag) at 300 kilobits/second, using the ISO MPEG-4 encoder to an AVI video file containing a single MPEG-4 video track. If you want to perform inverse telecine (IVTC) for NTSC source under Linux, you would need transcode, another nice program suite that provides useful video processing functionalities. It also is possible to encode the video in 2-pass mode to get the best result.

1st pass:

ffmpeg -i -an -pass 1 -passlogfile
-qscale 2 -vcodec mpeg4

2nd pass:

ffmpeg -i -an -pass 2 -passlogfile
-b 300 -vcodec mpeg4

The input file, the output file and the log file in both passes must be the same. Also, you should specify your desired bit rate during the second pass instead of the first.
Multiplexing: Combining the Video and Audio

After encoding the audio and video, it is time to combine them to create a real MPEG-4 clip. The MPEG4IP suite provides a nice tool called mp4creator for this purpose. It can add or remove tracks in an MPEG-4 file. But, let's first create the MPEG-4 clip by adding a video track:

mp4creator -c myvideo.avi -hint mytest.mp4

The -hint flag tells mp4creator to add an additional hint track for the video track. Hinting is required if you are streaming a clip with Darwin Streaming Server. If the mytest.mp4 file does not exist already, mp4creator creates it for you. To add an audio track, enter:

mp4creator -c myaudio.aac -hint -interleave mytest.mp4

Both commands perform a similar action. The second command introduced the -interleave flag, which creates an interleaved RTP payload format for the audio hint track. If you are using MP3 for your audio track (possibly not), ignore this flag as it supports only AAC. Finally, optimize the clip:

mp4creator -optimize mytest.mp4

This command optimizes the file layout, hence improving its speed during streaming. The rearranged MPEG-4 file contains control information at the beginning of the file, thereby enabling HTTP streaming of the file. To see a list of tracks in an MPEG-4 file, use:

mp4creator -list mytest.mp4

If you have a successful MPEG-4 clip, the list should look something like this (a clip currently being streamed at my school)

Using Amazon S3 to improve performance (using asp.net)

Most websites store a large number of media files. It may be photos, audio, video files etc. Of course that data takes up a lot of space on the server and, even more important, its eats your bandwidth and server resources. When we were working on Nuzizo we were faced with this problem. In order to improve performance, we setup an automated system using asp.net and Amazon S3.
Source(s):
http://www.linuxjournal.com/article/6720
http://www.wildbit.com/blog/2008/11/12/dynamic-rewriting-image-urls-on-aspn...


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