December 2023 - ffmpeg-user - lists.ffmpeg.org

Which file formats can hold image subtitles (dvdsub) without other streams
by bbb 04 Dec '23

04 Dec '23

Hi, I need a file format for a temporary file to store image subtitles (dvdsub) in. So far I've been using .mpg which generally works, but seems to be unable to keep the metadata. When I try to use mkv it insists on having a video stream (... figures). Is there a file format in which I can temporarily store subtitles alone and keep their metadata? Regards

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Mapping audio for non-surround audio
by MediaMouth 04 Dec '23

04 Dec '23

We've got two sources One video file (DNxHD36/mxf), no sound One wav file, 12 - 30 channels Together these two files are our mezzanine The goal is to merge the two into one multiple times, each time with different audio mapping So for instance one merge might be wav 1 - 14 map to output a1 wav 15-24 map to output a2 Another might be wav odd channels to output a1 wav even channels to output a2 And yet another might be wav 1-4 to output a1 wav 5-8 to output a2 wav 9-16 to output a3 etc Basically what's in our wav channels and how they get mixed and mapped is an ever-changing thing. Reading the ffmpeg documentation ( https://trac.ffmpeg.org/wiki/AudioChannelManipulation ) I haven't yet made sense of the logic in part because when it comes to mapping multiple channels, the assumption seems to be that you're working with surround and/mixing down to stereo In our case we're mixing down (or just mapping) from a large number of channels to anything, from mono to 24 tracks, and by googling alone I haven't (yet) figured out how to write the code for that in a reliable / schematic way. Thanks for any clarity on this.

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resululotion probem
by frhun 03 Dec '23

03 Dec '23

Hello I've posted a couple of times before, where it's for this reason or that reason, now my problem is that since q-scale was set to -g 2 the resolution has dropped drastically on the output. the interesting thing is that the speed out is the same as 720p, however on youtube it is good at a quarter of the resolution shown.. what should i adjust to make it good? I have set the -g switch in vain, but it hasn't changed. only the -presets switch made a difference. But it's interesting that when youtube complained about the bad starting frame, the picture was perfect, now it doesn't complain and the picture is terrible I am looking forward to your ideas, thanks in advance! Robert this is the ffmpeg structure ffmpeg -rtsp_transport tcp -i rtsp://xxx:xxxxx@192.168.0.24/Streaming/Channels/1 -c:v libx264 -b:v 2M -c:a aac -vf "[in]drawtext=fontfile='C\:\\Windows\\Fonts\\cour.ttf': textfile='c\:\\kolibry2\\verseny\\T_D\\Piros.txt': x=115: y=20: reload=1: fontcolor=black: fontsize=30: box=1: boxborderw=5: boxcolor=red(a)0.8 , drawtext=fontfile='C\:\\Windows\\Fonts\\cour.ttf': textfile='c\:\\kolibry2\\verseny\\T_D\\Feher.txt': x=115: y=55: reload=1: fontcolor=black: fontsize=30: box=1: boxborderw=5: boxcolor=white(a)0.8 , drawtext=fontfile='C\:\\Windows\\Fonts\\cour.ttf': textfile='c\:\\kolibry2\\verseny\\T_D\\Ora.txt': x=20: y=20: reload=1: fontcolor=black: fontsize=35: box=1: boxborderw=5: boxcolor=aqua(a)0.8 , drawtext=fontfile='C\:\\Windows\\Fonts\\cour.ttf': textfile='c\:\\kolibry2\\verseny\\T_D\\Merkozes.txt': x=20: y=53: reload=1: fontcolor=black: fontsize=28: box=1: boxborderw=5: boxcolor=yellow(a)0.8[out]" -preset medium -qscale 0 -g 2 -f flv rtmp://a.rtmp.youtube.com/live2/xxxxxx

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Image sequence with part pixelated with a mask
by Ric Hunter 02 Dec '23

02 Dec '23

Hello I want to convert an image sequence (jpg) into a mp4 but i want some part of the image sequence to be pixelated based on another mask image sequence (jpg, the white being pixelated, the black being not, but it can be png with alpha I don't mind, the simplest is the best) After a lot of digging and reading through documentations, exemples and what I could understand from it, I came up with that batch script (I want to use a batch script) *@echo offsetlocal enabledelayedexpansionset input_folder=C:\ffmpegblurtst\basepicsset mask_folder=C:\ffmpegblurtst\msk1set output_folder=C:\ffmpegblurtst\outputset filelist_path=%input_folder%\filelist.txtset masklist_path=%mask_folder%\filelist.txtset masksolo=%mask_folder%\realmask.pngset output_file=%output_folder%\output.mp4ffmpeg -r 30 -safe 0 -f concat -i "%filelist_path%" -i "%masklist_path%" -filter_complex "[0]scale=16:12[scaled];[scaled]scale=640:480:flags=neighbor[pixelated];[1]scale=640:480[ms];[pixelated][ms]alphamerge[okalpha];[okalpha][0]overlay" -c:v libx264 -pix_fmt yuv420p -b:v 10M "%output_file%"* Seems logical to me, but turns out it doesn't work and even doesn't read the image sequence of the mask. But even if I replace the image sequence with only one still image it still doesn't work.. I'd like to keep it in a single line and not use temporary files since I'd need to use this on thousands of frames. Thanks

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