I'm writing an application which need to capture screen. I've looked up for solution and internet says that FFMPEG could do it. But I can't find the way to do that IN CODE. FFMPEG documentation seems to be very poor.
Can anybody please tell me how do I access framebuffer raw data with FFMPEG?
FFmpeg supports input of rawframes throught stdin:
With the arg -f rawvideo ffmpeg will expect frames coming from stdin
ffmpeg -r 60 -f rawvideo -pix_fmt uyvy422 -s 1280x720 -i - -threads 0 -preset fast -y -pix_fmt yuv420p output.mp4
You can check this link, it has useful information.
In Qt, you would run a QProcess with ffmpeg with -f rawvideo and write to stdin with write() method.
This is roughly how to acomplish it:
QProcess* process;
process->start("ffmpeg.exe", args, QProcess::Unbuffered | QProcess::ReadWrite);
process->waitForStarted();
...
process->setProcessChannelMode(QProcess::ForwardedChannels);
videoFrame->GetBytes(&buffer);
process->write(buffer);
I have a c++ script that coneverts a series of jpg into a .mp4 video, the command i use is the folllowing:
std::system("ffmpeg -threads auto -y -framerate 1.74659 -i /mnt/ev_ramdsk/1/%05d-capture.jpg -vcodec libx264 -preset ultrafast /mnt/ev_ramdsk/1/video.mp4");
which produces a .mp4 video file like its supposed to except it cant be played from anywhere (tested in 2 computers and html5 video)
But, if from the same computer where the program runs, i do:
ffmpeg -threads auto -y -framerate 2 -i %05d-capture.jpg -vcodec libx264 -preset ultrafast video.mp4
from the command line, the output video plays wonderfully (except in vlc, for vlc i have to use -vcodec mpeg4)
What can possibly cause this behaviour?
could cp command corrupt the file? (ran after the mpeg to move it out of the ramfs)
EDIT:
As requested, i ran the whole set of commands one by one in the console exactly as the program do (the program logs every single command it runs, i just repeated them).
The commands are:
cp -r /var/cache/zoneminder/events/1/16/05/18/23/30/00/ /mnt/ev_ramdsk/1/
ffmpeg -threads auto -y -framerate 1.76729 -i /mnt/ev_ramdsk/1/%5d-capture.jpg -preset ultrafast /mnt/ev_ramdsk/1/video.mp4
cp /mnt/ev_ramdsk/1/video.mp4 /var/cache/evmanager/videos/1/2016_05_18_23_30_00_.mp4
The resulting .mp4 file can be played without any trouble. Also, is the only one with a preview image in the file explorer.
Thank you very much!
Solved it!
this was the winning answer. finally got it to work using:
std::system("ffmpeg -threads auto -y -r 1.74659 -i /mnt/ev_ramdsk/1/%05d-capture.jpg -px_fmt yuv420p -preset ultrafast -r 10 /mnt/ev_ramdsk/1/video.mp4");
Thank you very much!
So below is my command that I am running. It should be converting it to mp3 but it still exports as a video in flv. What am I doing wrong?
$cmd = '/usr/local/bin/youtube-dl -o "%(title)s.%(ext)s" -x --audio-format mp3 -- '.escapeshellarg($url).'';
youtube-dl will download the video before converting it. Most likely, you don't have ffprobe or ffmpeg installed. Make sure both programs are available (i.e. you get a sensible output for ffprobe --help and ffmpeg --help).
You can directly download the .mp3 file from the youtube site.
For e.g in ubuntu terminal youtube-dl youtube.com/watch?v=qn6CMz18lkQ -f 141 .Most probably 141 is the .mp3 file format code for better quality.
I'm using ColdFusion and need to generate a thumbnail from a flash movie stored on the server. I have heard of ffMpeg but have no idea how to use it. (Once you put it on your server what's the next step?)
You can use cfexecute to run a command line on the CF server.
Karthik linked a blog post that suggests the following syntax for ffmpeg:
ffmpeg -itsoffset -4 -i test.avi
-vcodec mjpeg -vframes 1 -an -f rawvideo -s 320x240 test.jpg
So you could do something like this:
<cfexecute
name="c:\pathto\ffmpeg\ffmpeg.exe"
arguments="-itsoffset -4 -i #sourcevideo# -vcodec mjpeg -vframes 1 -an -f rawvideo -s 320x240 #thumbnaildestination" />
I haven't run ffmpeg like this and you'll likely need to experiment with the syntax to get a result you like, but once you do your workflow is pretty straightforward.
You may also run into issues executing fmpeg.exe depending on the user account your ColdFusion server instance is running as.
Documentation of FFMpeg: http://www.ffmpeg.org/documentation.html
You might want to check: http://blog.prashanthellina.com/2008/03/29/creating-video-thumbnails-using-ffmpeg/
http://www.flashcomguru.com/index.cfm/2006/4/25/ffmpegthumbs
with ColdFusion its not possible but check this: http://old.nabble.com/Create-a-thumbnail-image-from-.flv-video-file-once-uploaded-td22683497.html
Original Question
I want to be able to generate a new (fully valid) MP3 file from an existing MP3 file to be used as a preview -- try-before-you-buy style. The new file should only contain the first n seconds of the track.
Now, I know I could just "chop the stream" at n seconds (calculating from the bitrate and header size) when delivering the file, but this is a bit dirty and a real PITA on a VBR track. I'd like to be able to generate a proper MP3 file.
Anyone any ideas?
Answers
Both mp3split and ffmpeg are both good solutions. I chose ffmpeg as it is commonly installed on linux servers and is also easily available for windows. Here's some more good command line parameters for generating previews with ffmpeg
-t <seconds> chop after specified number of seconds
-y force file overwrite
-ab <bitrate> set bitrate e.g. -ab 96k
-ar <rate Hz> set sampling rate e.g. -ar 22050 for 22.05kHz
-map_meta_data <outfile>:<infile> copy track metadata from infile to outfile
instead of setting -ab and -ar, you can copy the original track settings, as Tim Farley suggests, with:
-acodec copy
I also recommend ffmpeg, but the command line suggested by John Boker has an unintended side effect: it re-encodes the file to the default bitrate (which is 64 kb/s in the version I have here at least). This might give your customers a false impression of the quality of your sound files, and it also takes longer to do.
Here's a command line that will slice to 30 seconds without transcoding:
ffmpeg -t 30 -i inputfile.mp3 -acodec copy outputfile.mp3
The -acodec switch tells ffmpeg to use the special "copy" codec which does not transcode. It is lightning fast.
NOTE: the command was updated based on comment from Oben Sonne
If you wish to REMOVE the first 30 seconds (and keep the remainder) then use this:
ffmpeg -ss 30 -i inputfile.mp3 -acodec copy outputfile.mp3
try:
ffmpeg -t 30 -i inputfile.mp3 outputfile.mp3
This command also works perfectly.
I cropped my music files from 20 to 40 seconds.
-y : force output file to overwrite.
ffmpeg -i test.mp3 -ss 00:00:20 -to 00:00:40 -c copy -y temp.mp3
you can use mp3cut:
cutmp3 -i foo.mp3 -O 30s.mp3 -a 0:00.0 -b 0:30.0
It's in ubuntu repo, so just: sudo apt-get install cutmp3.
You might want to try Mp3Splt.
I've used it before in a C# service that simply wrapped the mp3splt.exe win32 process. I assume something similar could be done in your Linux/PHP scenario.
I have got an error while doing the same
Invalid audio stream. Exactly one MP3 audio stream is required.
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argumentStream mapping:
Fix for me was:
ffmpeg -ss 00:02:43.00 -t 00:00:10 -i input.mp3 -codec:a libmp3lame out.mp3
My package medipack is a very simple command-line app as a wrapper over ffmpeg.
you can achieve trimming your video using these commands:
medipack trim input.mp3 -s 00:00 -e 00:30 -o output.mp3
medipack trim input.mp3 -s 00:00 -t 00:30 -o output.mp3
you can view options of trim subcommand as:
srb#srb-pc:$ medipack trim -h
usage: medipack trim [-h] [-s START] [-e END | -t TIME] [-o OUTPUT] [inp]
positional arguments:
inp input video file ex: input.mp4
optional arguments:
-h, --help show this help message and exit
-s START, --start START
start time for cuting in format hh:mm:ss or mm:ss
-e END, --end END end time for cuting in format hh:mm:ss or mm:ss
-t TIME, --time TIME clip duration in format hh:mm:ss or mm:ss
-o OUTPUT, --output OUTPUT
you could also explore other options using medipack -h
srb#srb-pc:$ medipack --help
usage: medipack.py [-h] [-v] {trim,crop,resize,extract} ...
positional arguments:
{trim,crop,resize,extract}
optional arguments:
-h, --help show this help message and exit
-v, --version Display version number
you may visit my repo https://github.com/srbcheema1/medipack and checkout examples in README.