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Video podcast
???
Audio only mp3 player
I'm looking for somewhere which will extract audio from video, but instead of a single file, for an on going video podcast.
I would most like a website which would suck in the RSS and spit out an RSS (I'm thinking of something like Feedburner), though would settle for something on my own machine.
If it must be on my machine, it should be quick, transparent, and automatic when I download each episode.
What would you use?
Edit: I'm on an Ubuntu 8.04 machine; so running ffmpeg is no problem; however, I'm looking for automation and feed awareness.
Here's my use case: I want to listen to lectures at Google Video, or Structure and Interpretation of Computer Programs. These videos come out fairly often, so anything that's needed to be done manually will also be done fairly often.
Here's one approach I'd thought of:
download the RSS
parse the RSS for enclosures,
download the enclosures, keeping a track what has already been downloaded previously
transcode the files, but not the ones done already
reconstruct an RSS with the audio files, remembering to change the metadata.
schedule to be run periodically
point podcatcher at new RSS feed.
I also liked the approach of gPodder of using a post-download script.
I wish the Lazy Web still worked.
You could automate this using the open source command line tool ffmpeg. Parse the RSS to get the video files, fetch them over the net if needed, then spit each one out to a command line like this:
ffmpeg -i episode1.mov -ab 128000 episode1.mp3
The -ab switch sets the output bit rate to 128 kbits/s on the audio file, adjust as needed.
Once you have the audio files you can reconstruct the RSS feed to link to the audio files if so desired.
How to extract audio from video to MP3:
http://www.dvdvideosoft.com/guides/dvd/extract-audio-from-video-to-mp3.htm
How to Convert a Video Podcast to Audio Only:
http://www.legalandrew.com/2007/03/10/how-to-convert-a-video-podcast-to-audio-only/
When you edit your video, doesn't your editor provide you an option to split out the audio?
What platform is your own machine? What format is the video podcast?
You could possibly get Handbrake to do this (Windows, Linux and Mac), I don't know if it's scriptable at all but I think it can be used to separate audio and video.
edit: There is a commandline interface for Handbrake, but it appears I was wrong about it accepting non-DVD input.
On the Mac I'd probably rig up something with Applescript and QuickTime - what platform are you on?
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I have an IP camera (Axis M1054) and I would like to record video stream. I would probably start with continuous recording, but then I would like to switch to clips triggered by motion detection (with pre-rec of couple seconds before the trigger occured), recording being encoded in MPEG4 (H.264), not in MJPEG.
Is there a free open source Linux software that can do it? I did not find anything by searching the Internet. Can you recommend something that works and you successfully use? Or am I stuck with commercial software?
I have no problem replacing the camera if different model would work better with Linux.
What about giving a try to open source openh264 backed by Cisco? It supports Long Term Reference (LTR) frames which might help you with motion detection.
I've found Motion to be a great program for motion detection and cataloging.
It seems to work with remote cameras, although the docs are a bit sketchy. It's probably worth a try.
I use the linux Motion software combined with the command line version of VLC for my IP cameras. (2 are MJPG streams, one is RTSP with H264). The motion software triggers a script to have VLC record lossless in the cameras native format. My setup does not however support pre-recording. It actually results in missing the frame that initially triggered the motion which is fine for my use since the first frames of motion are not where I'd see the faces or license plates.
Your camera streams H.264 over RTP controlled by RTSP. You need a RTP client to connect to the camera in order to get to the streams.
http://www.live555.com provides a RTSP client library with a variety of sample code.
First I would try http://www.live555.com/openRTSP/ from the command line.
I have successfully used live555 to record a variety of IP cameras.
You could also use the FFMPEG library:
Receiving RTSP stream using FFMPEG library
FFMPEG also takes care of muxing (creating a container file) or decoding.
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I've looked for references on the Audible format, and it appears that people are only interested in cracking/converting out of it. I've got a collection of MP3 files that I want to convert into Audible format for use on my Kindle and iPod.
Does anybody have a good reference on the Audible or protected AAC formats and how section markers and metadata are expressed? Better yet, a utility or code sample?
The Audible format is a DRM protected proprietary format only available from Audible. They protect their format diligently. From what I understood, they used to charge handsomely for the right to use it. I am not aware of any publicly available encoders that will create audible formatted files (for free or not). Since Amazon bought Audible I am not sure if they would even sell the right to anyone else anymore.
I do not own a Kindle, but from what I can tell, it only supports Audible formatted files with full audiobook functionality. MP3's can be played , but they are not treated the same way (no support for chapters etc).
Creating audiobooks with chapter support for the iPod requires creating a M4B file with a text track and making sure the audio track has the proper track reference to the text track. M4B is a version of MP4 that uses AAC audio. There are several programs to do this on the MAC and recently a few have surfaced for the PC.
I have created a freeware software package with a Graphical User Interface (GUI) for the PC which is in Beta test now. It is called "Chapter and Verse" and it will be available on lodensoftware.com shortly. Two other options with GUI's are: "Chapter Master" from Rightword Enterprises ($15) and "iPod Audio Book Converter" (freeware) from sjhaley.com which is in Beta test as well.
Several command line utilities exist as well. One is called Slide Show Assembler (SSA) that can be used to create podcasts as well as audiobooks. SSA is available from jrlearnsmedia.com. Another is a command line utility for manipulating MP4 files called mp4creator. mp4creator can add chapters to a MP4 file.
I struggled with the problem of mp3 to m4b audiobooks on OSX for a while and came up with my workflow.. now summed up in a ruby script that does it all automatically. Here's the workflow:
1.(ruby) sort files and identify chapter names (regexp magic!)
2.(lame) convert all the mp3 to 64kbits mono cbr (this is done to leverage the input files, remove tags that could cause problems in merging, and most of all because coreaudio aac conversion from stereo to mono sucks..)
3.(mp3info ruby gem) compute files length and generate chapter xml file (length computed on the mono cbr version to avoid problems)
4.(cat) merge them
5.(afconvert) convert to aac
6.(ChapterTool) applay chapter markers and rename to m4b
FYI
Chapter and Verse has been released for some time.
The latest version (v1.3) is now available with full capability to create chapterized audiobooks with chapter images for the iPod, iTunes and quicktime.
The program is freeware and is available at lodensoftware.com
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We need to capture live video and display easily on Linux. We need a cheap card or USB device with a simple API. Anyone want to share some experience?
Use the video4linux library. I've used it with a c++ program and was able to capture webcam frames within about an hour. (Very easy to use and setup)
If you need to program, you're best off using GStreamer, a multimedia framework under Linux.
Cheese, mentioned by jackbravo, is based on GStreamer, as is Flumotion, a streaming server I work on.
As mentioned, Use dvgrab to capture from a Firewire interface from the camera, then use tools such as ffmpeg (command line) or kino (simple gui video editor) to process the video as needed. PCI based Firewire cards are relatively inexpensive and easy to find.
Here are some examples:
continuous capture from firewire, autosplit every couple of minutes
dvgrab --size 500 --autosplit <filename>
watch the camera live
dvgrab - | mplayer -
Be aware that some recent distros (e.g. Fedora8) are using new but half-baked firewire drivers. However, Ubuntu works great.
There are "sealed" camera solutions out there with mini-webservers and an ethernet port on the back. Just plug it in to the network, set its IP, and open up a browser... in linux or wherever
If you want to capture in linux, I once had a cheap webcam capturing single frames in a perl script, which could have been modified for real time - though that was about 10 years ago. Anyway, its possible :-/
There's the cheese gnome application. Really simple to use. Not too much features, just video capture.
openCV will allow you to capture individual frames from a camera and save to disk. If you need to then manipulate these to create a video, I would suggest netpbm, a pretty powerful set of command line tools you can use with some shell scripting to make a video or do whatever it is you need.
Another option is to use Firewire (IEEE1394) cameras, such as most common DV camcorders. They tend to work really well and give a lot better video than cheap web cams, and there is a plethora of tools in Linux for working with dv video, such as dvgrab.
If you use java, v4l4j makes it very simple to capture frames from any V4L device. It also allows you to control the device from java. I used it with a PTZ webcam (logitech quickam orbit), and I could control usual thigs like brightness, saturation and auto-white balance, but also the tilt and pan of the camera. Very handy !
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Part of a new product I have been assigned to work on involves server-side conversion of the 'common' video formats to something that Flash can play.
As far as I know, my only option is to convert to FLV. I have been giving ffmpeg a go around, but I'm finding a few WMV files that come out with garbled sound (I've tried playing with the audio rates).
Are there any other 'good' CLI converters for Linux? Or are there other video formats that Flash can play?
Flash can play the following formats:
FLV with AAC or MP3 audio, and FLV1 (Sorenson Spark H.263), VP6, or H.264 video.
MP4 with AAC or MP3 audio, and H.264 video (mp4s must be hinted with qt-faststart or mp4box).
ffmpeg is an overall good conversion utility; mencoder works better with obscure and proprietary formats (due to the w32codecs binary decoder package) but its muxing is rather suboptimal (read: often totally broken). One solution might be to encode H.264 with x264 through mencoder, and then mux separately with mp4box.
As a developer of x264 (and avid user of flash for online video playback), I've had quite a bit of experience in this kind of stuff, so if you want more assistance I'm also available on Freenode IRC on #x264, #ffmpeg, and #mplayer.
Most encoders, by default (ffmpeg included) put the header atom of the mp4 (the "moov atom") at the end of the video, since they can't place the header until they're done encoding. However, in order for the file to start playback before its done downloading, the moov atom has to be moved to the front.
To do this, you have to (re)mux using mp4box (which does it by default) or use qt-faststart, a script for ffmpeg that simply moves the atom to the front. Its quite simple.
Note that for FLV, by default, ffmpeg will use the FLV1 video format, which is pretty terrible; its over a decade old by this point and its efficiency is rather awful given modern standards. You're much better off using a more modern format like H.264.
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What is a good free library for editing MP3s/FLACs.
By editing I mean:
Cutting audio file into multiple parts
Joining multiple audio files together
Increase playback speed of file without affecting the pitch (eg. podcasts up to 1.3x)
Re-encoding audio file from Flac -> MP3 or vice versa
I don't mean software, I mean a library that I can use within another application. Programming language agnostic.
Just about every language has bindings to C, so you'll probably want to get the applicable C libraries for encoding/decoding mp3's and FLAC files. This list might include
libFLAC http://flac.sourceforge.net/api/index.html FLAC encoding/decoding
LAME http://lame.sourceforge.net/index.php MP3 encoding
MAD http://www.underbit.com/products/mad/ MP3 decoding
The rest of your signal processing needs could be gathered around a single popular API such as LADSPA http://www.ladspa.org/.
Here's a stretching / pitch shifting library: http://www.breakfastquay.com/rubberband/
Most audio processing programs have a certain internal format they use. That keeps things simple. Everything coming in gets converted to the same format. Once you've standardized the internal format, cutting and splicing audio data is about as difficult as cutting and splicing strings. You don't really need a library for that.
I use Audacity for all my editing needs
Audacity is a free, easy-to-use audio
editor and recorder for Windows, Mac
OS X, GNU/Linux and other operating
systems. You can use Audacity to:
* Record live audio.
* Convert tapes and records into digital recordings or CDs.
* Edit Ogg Vorbis, MP3, WAV or AIFF sound files.
* Cut, copy, splice or mix sounds together.
* Change the speed or pitch of a recording.
Audacity uses the Lame library, however not only is this not language agnostic it also has some questions over licensing. Nevertheless it might be a start