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• How do I run the qt ffmpeg wrapper example ? (error : cannot find -lavutil)

  29 août 2013, par James

  I am using QT 4.8 on the raspberry pi trying to save a binary stream to a video file like mp4. I was able to create and save static images by converting it into a QImage, but QT does not seem to support actually saving that stream (or the series of QImages) to a video file.

  The only option I may have found is qt ffmpeg Wrapper
  https://code.google.com/p/qtffmpegwrapper/

  but the example won't run out of the box. I am having the same exact problem as this guy :

  https://code.google.com/p/qtffmpegwrapper/issues/detail?id=14&colspec=ID%20Type%20Status%20Priority%20Milestone%20Owner%20Summary%20Opened%20Closed%20Modified#makechanges

  All I did was download it and try to run the included example, but no go.
  Am I supposed to download ffmpeg files prior to using this ? apt-get install ffmpeg ?

  Thanks !

• FFMPEG using wrong arguements when refering to image files

  14 août 2013, par Chad Marmon

  I am creating a bat file that will use FFMPEG to convert Real Media files to .MP4 files. I am looping though the current folder and finding files with the .rm extension adding several pictures to the video files to create a slide show effect in the final product.

  With this code here it works except it only shows one static image :

  for %%a in ("*.rm") do ffmpeg -f image2 -r 1/5 -i "img00.jpg" -i "%%a" -c:v libx264 -r 30 -preset slow -crf 20 -c:a libvo_aacenc -b:a 48k -b:v 16k "newfiles\%%~na.mp4"

  With this code it should show a series of photos. However it does not :

  for %%a in ("*.rm") do ffmpeg -f image2 -r 1/5 -i "img%02d.jpg" -i "%%a" -c:v libx264 -r 30 -preset slow -crf 20 -c:a libvo_aacenc -b:a 48k -b:v 16k "newfiles\%%~na.mp4"

  I get this error when I run the second piece of code :

  Could find no file with with path 'imgC :\Data\RealtoMP\FFMPEG_JPG\ffmpegA48V16_AudOnly' and index in the range 0-4
  imgC :\Data\RealtoMP\FFMPEG_JPG\ffmpegA48V16_AudOnly : No such file or directory

  It appears to me that it is somehow instead of getting the range argument like it should, it's injecting the path to the file that I am running. Any ideas of what is causing this ?

  EDIT :

  I fixed my problem by escaping the %02 with another %. The result is %%02 for it to act correctly in the script.

• what is the packet size unit of ffprobe(similar to ffmpeg) ?

  26 août 2014, par Juneyoung Oh

  I am developing thumbnail extractor with ff- series(means ffmpeg, ffplay, ffprobe).

  I need to know the location of frames, so I use a command like below which I found another posting in stackoverflow.

  ffprobe -show_frames -select_streams v -print_format json=c=1 0001.wmv

  Actually it works nice and makes a file with lots of information of packet.

  The output file like below.

     "frames": [
  
          { "media_type": "video", "key_frame": 1, "pkt_pts": 900000, "pkt_pts_time": "10.000000", "pkt_dts": 900000, "pkt_dts_time": "10.000000", "pkt_duration": 3003, "pkt_duration_time": "0.033367", "pkt_pos": "453", "pkt_size": "9744", "width": 720, "height": 480, "pix_fmt": "yuv420p", "sample_aspect_ratio": "8:9", "pict_type": "I", "coded_picture_number": 0, "display_picture_number": 0, "interlaced_frame": 0, "top_field_first": 0, "repeat_pict": 0 },...

  There is a column named "pkt_size", which I assume that size of packet.

  It displays some numbers in, but no information of units.

  I wonder that unit is ’byte’ or ’bit’.

  If somebody has some information of this, Tell me.

  Thanks.