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• Resume transcoding a video with ffmpeg

  25 novembre 2014, par Jonathan.

  I have a node server that uses child-process to use ffmpeg to convert a video to mp4. However if the server crashes while transcoding, then I’d like to resume transcoding the file (similar to -C with curl).

  I figured I could just start transcoding the file from where it finished to a seperate file and then just concat the two. And while transcoding the file from where it finished works and the file that starts midway plays back fine, when I concat the two files with ffmpeg -i "concat:part1.mp4|part2.mp4" -c copy ouput.mp4 Only the first part will play, and when it gets to the second part it just stays on the last frame of the first part or goes black depending on the video player. (But playing part2.mp4 itself works fine)

  There isn’t any error during either conversion or the concat.

• Why UA sniffing is generally bad, real-world example #1048577 : "That time a missing /s on navigator.userAgent (based on single-digit UA version assumptions) broke SM2 on iOS 8+ devices."

  1er septembre 2014, par scottschiller

  Why UA sniffing is generally bad, real-world example #1048577 : "That time a missing /s on navigator.userAgent (based on single-digit UA version assumptions) broke SM2 on iOS 8+ devices."
  The upside : The fix is adding \s to a UA regex check targeting legacy iOS devices with broken HTML5 Audio support, so that the "OS 10 " portion of the UA string does not match the pattern "OS 1 ".
  This is a pre-emptive fix for the pending iOS 8 release, which reportedly includes the string "iPhone OS 10_10 like Mac OS X". Due to SM2 checking for /os ([12|3_0|3_1])/i which had broken HTML5 Audio() support, and not considering the far future possibility of "iOS 10" being included in the userAgent string at the time, HTML5 audio is incorrectly disabled on iOS 8 beta 3 and is likely to apply to the final iOS 8 release.
  This is a good example and reminder of why UA checks are generally bad, and dangerous ; similar issues hit other libraries doing UA and plugin checks both client and server-side when IE hit 10, and Flash hit version 10, so this iOS pattern change may affect some other libraries targeting iOS as well.
  

• No such file or directory FFMpeg Error on MAC

  20 novembre 2014, par Nitesh

  I am trying to build a ffmpeg binary using the following link

  http://ffmpegmac.net/HowTo/

  I was successful in creating the binary.
  I could convert video files easily
  This is the code i run in the terminal

  ffmpeg -i Test.mp4 -b:v 64k -bufsize 64k test2.flv

  This works fine totally
  But when i run

  ./ffmpeg -re -i  test2.flv  -acodec libfaac -ar 44100 -ab 96k -c: v libx264  -level 41 -      profile baseline -bufsize 20000k -maxrate 25000k -g 250 -r 20 -s 480x270 -flags  -global_header -map 0 -f segment -segment_time 4 -segment_list test.m3u8 -segment_format mpegts stream%05d.ts 

  I get a "test2.flv : No such file or directory error" even though the test2.flv exists in the folder. Can you tell me where i might be going wrong.
  I am doing the above operation to stream the video to my iPhone over air.

  (Note- The command to build the ffmpeg binary i am using is as follows-
  ./configure —prefix=$TARGET —enable-nonfree —enable-gpl —enable-pthreads —enable-version3 —enable-libspeex —enable-libvpx —disable-decoder=libvpx —enable-libfaac —enable-libmp3lame —enable-libtheora —enable-libvorbis —enable-libx264 —enable-avfilter —enable-libopencore_amrwb —enable-libopencore_amrnb —enable-filters —arch=x86_64 —enable-runtime-cpudetect && make -j 4 && make install
  )

  Thanks in advance for your help
  Regards