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• FFMPEG : Mapping YUV data to output buffer of decode function

  22 décembre 2013, par Zax

  I am modifying a video decoder code from FFMPEG. The decoded code is of format YUV420. I'm having 3 pointers, each pointing to Y, U and V data i.e :

  yPtr-> is a pointer pointing to the Luma
  
  uPtr-> is a pointer pointing to the Chroma Cb
  
  vPtr-> is a pointer pointing to the Chroma Cr

  However, the output pointer to which I need to map my YUV data is of type void. And the output pointer is just one.

  i.e : void *data is the output pointer for which I need to point my yPtr, uPtr and vPtr. How should I do this ?

  One approach I have tried is, created a new buffer whose size is equal to the sum of Y, U and V data, and copy the contents of yPtr, uPtr and vPtr to the newly allocated buffer, and the pointer to this buffer I'm allocating to *data output pointer.

  However this approach is not preferred because memcpy needs to be performed and other performance drawbacks.

  Can anyone please suggest an alternative for this issue. This may be not related directly to FFMPEG, but since I'm modifying FFMPEG's libavcodec's decoder code, I'm tagging it in FFMPEG.

  Edit : What I'm trying to do :

  Actually my understanding is if I make this pointer point to void *data pointer of any decode function of any decoder and setting *got_frame_ptr to 1, the framework will take care of dumping this data into the yuv file. is my understanding right ?

  The function prototype of my custom video decoder or any video decoder in ffmpeg is as shown below :

  static int myCustomDec_decode_frame(AVCodecContext *avctx,
  
              void *data, int *data_size,
  
              uint8_t *buf, int buf_size) {

  I'm referring to this post FFMPEG : Explain parameters of any codecs function pointers and assuming that I need to point *data to my YUV data pointer, and the dumping stuff will be taken care by ffmpeg. Please provide suggestions regrading the same.

• FFmpeg & Installation on phpmyadmin [migrated]

  18 septembre 2011, par Vivek

  I am attempting to have an interface in which people can upload music files and listen to them through the site. The biggest problem obviously is that someone who uploads an audio track in mp3 format into Mozilla wouldn't be able to play it back (since MF doesn't support mp3 playback since I'm using jPlayer).

  I did some research and found out that I could use command line php using FFmpeg to convert the mp3 to ogg or some other supportable format. I believe I understand (a little bit) how command line php works but I was wondering how I could install it onto phpmyadmin on my hosting service ? Could anyone link me to a tutorial or care to explain ? I tried googling it but I just couldn't find it.

• Python Lambda function and ffmpeg command with stdout from jpg to ts file

  28 juillet 2021, par Sflagg

  I have a AWS Lambda Python function setup to process jpg and convert it to a ts file.

  


  I followed these instructions https://aws.amazon.com/blogs/media/processing-user-generated-content-using-aws-lambda-and-ffmpeg/ but changed the command from vfr to cfr conversion to a jpg to ts conversion.

  


  This is the command I am using

  


  ffmpeg_cmd = "/opt/bin/ffmpeg -r 30000/1001 -loop 1 -i \"" + s3_source_signed_url + "\" -f lavfi -i anullsrc=channel_layout=stereo:sample_rate=48000 -t 30 -vcodec libx264 -crf 23 -s 1920x1080 -r 30000/1001 -g 150 -pix_fmt yuv420p -acodec aac -b:a 96k -ar 48000 -"

  


  Everything else is basically the same from the AWS article besides having s3 triggers in my Lambda look for jpeg and jpg suffixes.

  


  But this results in 0 byte ts file.

  


  I have a hunch that I need to modify the command that has a seekable output format (e.g. mpegts) when writing to stdout ; currently my command is likely not working for stdout and that is why I get an empty ts file. But I am having trouble formatting the command correctly. Any help with this would be greatly appreciated !