It appears that windows is incompatible with some of the shelling parts of my python script, so I have uploaded a windows specific version to take care of these issues.
Issues are:
Download: pbox2avi_win.py
So I just finished another round of grad finals yesterday. I’ve been meaning to update the blog with some other useful or interesting projects that I’ve been playing around with in my spare time.
Now last week, a friend of mine from my wonderful Cal days, came down from UCSF (med student) for a concert at Stanford. He dropped by afterwards to catch up. Lucky for him, (and future UCSF students) he and his friends (amusing) mentioned that poor UCSF med students have these silly lecture “videos” in swf format, instead of standard web streamed video that Stanford and Cal both have abundantly. The great thing about video is that you can fast forward people. 2 hour lectures become 1!
Of course, having just finished the SCPD video downloading strips, I figured that it was probably video embedded in an swf video player. Turns out, it’s actually a bunch of pictures and audio. There’s no actual video! Apparently what happens is they take pictures every so often and then record sound, take another picture record the sound that goes with it. So, being the nerd I am, I had to try to see if I could convert it to video. So my friend sends me a sample link later that night. Thus, began my Pbox (that’s what they call it) to avi endeavor.
Before I briefly describe the process, I set certain goals I had to make.
To cut a long story short, I researched different ways of extract data from swf flash files. It turns out that swftools is a crossplatform (with precompiled binaries) for linux, os x, and windows. After figuring out how swfextract works, I realized that I would have to make a video clip of the presentation slide and the corresponding audio clip. To do that, I found mjpegtools, a cross-platform picture-to-video set of tools. To add the audio and video, I resorted to using my familiar tool mencoder. However, I had to make sure that the picture-video was exactly as long as the audio. I resorted to using exiftool, a program that parses tags of stuff. Last but not least, to automate all these tools, so a med student wouldn’t have to know how any of them worked, I used python to glue them altogether.
Requirements:
Usage:
python pbox2avi.py [lecture.swf] [output.avi]Speed:
If you’re a UCSF med student and you benefit from this conversion utility, and you feel like you would like to repay me somehow, feel free to send me an email. Since I’m working on biocomputational cardiac modeling, any future cardiologists, I would like to talk to you!
If you have questions, as usual feel free to leave a comment. Or if you know my friend at UCSF, you can ask him.
Code:
# python script to extract lecture slides and mp3's from UCSF lecture files for conversion #requires swfextract import commands,sys,re def parse(filename): #check filename for .swf extension if not filename.find('.swf'): # not a comprehensive check return #open file status, output = commands.getstatusoutput("swfextract %s" % (filename,)) print output #find "JPEGs: ID(s)" slide_identifier = "JPEGs: ID(s)" start=output.find(slide_identifier) slide_extract=[] if start: start += len(slide_identifier)+1 slide_end = output.find("[-s]",start) print start,slide_end slide_extract=output[start:slide_end-2].replace(" ","") #find "Sounds: ID(s)" sound_identifier = "Sounds: ID(s)" start=output.find(sound_identifier) sound_extract=[] if start: start += len(sound_identifier)+1 sound_end = output.find("[-f]",start) sound_extract=output[start:sound_end-2].replace(" ","") # now extract all the data print "swfextract %s -P -j %s -s %s" % (filename,slide_extract,sound_extract) status, output = commands.getstatusoutput("swfextract %s -P -j %s -s %s" % (filename,slide_extract,sound_extract)) return slide_extract,sound_extract def create(slide_extract,sound_extract,outputfile): #first throw out every other picture because second picture is always a thumbnail slides=slide_extract.replace(","," ").split(" "); slides=[slides[i] for i in range(len(slides)) if i%2 ==0] sounds=sound_extract.replace(","," ").split(" "); print "Number of slides: %s, number of mp3's: %s" % (len(slides),len(sounds)) for i in range(len(sounds)): vidcmd="jpeg2yuv -n %d -I p -f 2 -j %s | yuv2lav -o temp.avi" % (int(round(2*10*(duration("sound%s.mp3" % (sounds[i],))))/10),"pic%s.jpg" % (slides[i],)) # print vidcmd status,output=commands.getstatusoutput(vidcmd) sndcmd="mencoder temp.avi -o slide%d.avi -ovc lavc -lavcopts vcodec=msmpeg4 -oac copy -audiofile sound%s.mp3" %(i,sounds[i]) # print sndcmd commands.getstatusoutput(sndcmd) print "Finished processing slide %d" % (i,) print "Cleaning up..." # remove unnecessary data commands.getstatusoutput("rm *.jpg *.mp3 temp.avi") slidevids=["slide%s.avi" % (i,) for i in range(len(slides))] slidevids=" ".join(slidevids) print "Combining slides..." # combine all of them commands.getstatusoutput("mencoder -oac copy -ovc copy %s -o %s" % (slidevids,outputfile)) print "Cleaning up..." commands.getstatusoutput("rm slide*.avi") def duration(mp3): # find duration of mp3 using exiftool cmd="exiftool -Duration %s" % (mp3,) status,output = commands.getstatusoutput(cmd) time=output[output.find(":")+1:output.find("(approx)")-1] reg=re.compile(r"(\d+):(\d+)|([\d\.]+) s") timestr=reg.search(time) #print time,timestr Min,Sec,Secs=timestr.groups() #print Min,Sec,Secs if Secs==None: # in terms of minutes return int(Min)*60+int(Sec) else: return float(Secs) if __name__=="__main__": slides,sounds=parse(sys.argv[1]) if len(sys.argv)==2: create(slides,sounds,"output.avi") elif len(sys.argv)==3: create(slides,sounds,sys.argv[2]) |
Since I am currently attending Stanford, and I once searched the intraweb for a solution for downloading wmv streams, but couldn’t find anything specific, I’ll post my solution here.
Normally, SCPD requires you to login and then you watch the videos streamed using some wmv player. However, should you want to rewind or seek through a stream, this will prove to be impossible. Many commercial wmv recorders are not free, and simply play the video to download it. My solution is similar to this, but it is FREE (as in beer).
What you need:
To download from SCPD (or other unprotected wmv streams), simply execute the following at a command prompt:
mencoder mms://stream.wmv -ovc copy -oac copy -o output.aviIt will throw a bunch of text to the screen, and you simply leave the window open (or minimized) and wait for it to finish. However, since it’s free, I commonly download several streams at the same time, so when they are done I will have several streams downloaded instead of just one.
Download: Greasemonkey script for SCPD (gets links automatically when you view an SCPD video) (Updated 9/29/09)
If you are lazy like me, and don’t want to change the http://url to mms://url I’ve provided an mencoder script that, given an http url, will fill out the commandline and execute it for you. (Note: Many mac and linux users will have python already installed on their machines.)
Usage:
./stripSCPD http://urlDownload: Python SCPD script
#!/usr/bin/python import subprocess,sys def strip(url): newurl = "mms"+url[url.find(":"):] print newurl vidname = url[url.rfind("/")+1:url.rfind("?")] print "mencoder %s -ovc copy -oac copy -o %s.avi" % (newurl,vidname) subprocess.Popen(["mencoder", newurl, "-ovc","copy","-oac","copy","-o", ("%s.avi" % (vidname,))]) if __name__=="__main__": strip(sys.argv[1]) |
Update (11/09/08):
I’ve just tried everything again in windows, and it seems to work. Note, for some reason mplayer doesn’t have the necessary codecs by default in the downloadable zip file. However, VLC, media player classic and Windows media Player seem to be able to seek. However only media player classic can increase the audio speed (in case you want to watch a stream 1.5 times fast and be able to comprehend what someone is saying even if they seem to be on helium!).