April 2018 - ffmpeg-user - lists.ffmpeg.org

Drawtext multicolor
by Gianluca F. 05 Apr '18

05 Apr '18

Hi all, I know that probably, there is no solution to my problem, but the answers on dedicated forums are old and , who knows, it may happens that something has changed during the time! I need to draw multiple vertical and horizontal lines , and I'd like to use different colors for some words in lines. Actually, each row is a single drawtext filter, and to align all texts vertically, I have had to extract the "th" of each row, to properly set the vertical position; a semi-nightmare. To draw words with different colors, on each line, I should draw multiple drawtexts horizontally, but the vertical alignment of drawtexts of each line, probably will be a FULL nightmare, because obviusly, each texts will have different heights! And cause each line has a boxborder, also 1 pixel of difference will be evident. Also, there is the problem of horizontal alignment ... A very ( apparently ) simple task made ( almost ) impossible, but I see so many text on Internet video, with different words color, that I wander how do they do that. I know that there is fontcolor_exp, but I know that it does not accept something like "chart position", only the "t" time. Is there a solution to draw a text with multicolor using a single drawtext? Thanks in Advance

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Re: [FFmpeg-user] How to drop frames to limit memory usage (or keep latency low)?
by Victor Carneiro Fardim 05 Apr '18

05 Apr '18

Hi, Adam. I don't see any way to do automatic frame skipping in FFmpeg. What you could do is reduce the output framerate by using the `-r (framerate)` or the `fps` video filter, which will reduce the encoding load on the CPU. Adjust this until the average encoding throughput is 1.00x (that means, when the average number of frames encoded per second is equal to the specified framerate, and your average CPU load is below ~90% just to be safe). Also, I'm sure `mpeg2video` does not support encoding presets. If you want fast encoding, you may want to try `libx264` with `-preset ultrafast`, `-tune stillimage` and `-deblock 0:0`, since that can be faster than MPEG-2 depending on your CPU architecture, and maybe more efficient. If available on your platform, you may also want to try hardware-accelerated H 264 encoding APIs. You can find some info here: https://trac.ffmpeg.org/wiki/HWAccelIntro (note: you may have to compile a custom build of FFmpeg to enable this feature, as pre-built ones aren't usually compiled for it. Victor Carneiro

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libharfbuzz linking error when trying to compile FFmpeg.
by Victor Carneiro Fardim 04 Apr '18

04 Apr '18

Hello. So, I'm trying to compile a custom build of FFmpeg, but whenever it gets to the executable linking stage, it fails with the following message: LD ffmpeg_g /usr/lib/libharfbuzz.so.0: undefined reference to `FT_Done_MM_Var' /usr/lib/libharfbuzz.so.0: undefined reference to `FT_Get_Var_Blend_Coordinates' collect2: error: ld returned 1 exit status make: *** [Makefile:107: ffmpeg_g] Error 1 I'm running Manjaro GNU/Linux, all of my packages are up to date, and I'm building from the latest official Git commit. My freetype and harfbuzz packages are both from the official Manjaro repositories and are up-to-date - from what I've read, this error usually occurs with unofficial freetype and harfbuzz builds, which is not the case. My ./configure command looks like this: export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig/ && ./configure --prefix=/usr --enable-gpl --enable-version3 --enable-libopus --enable-libcodec2 --enable-libmp3lame --enable-libx265 --enable-libaom --enable-libfreetype --enable-libvpx --enable-libv4l2 --enable-libx264 --enable-libass --enable-libpulse --enable-libvorbis --enable-libwebp --enable-libtheora I'd appreciate your help with this problem. I'll also be posting this issue on the Manjaro forums to see if anyone is able to reproduce/give me some insight on the problem. Thanks in advance and good encodes for all of you, Victor Carneiro

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Question about using ffmpeg to convert a sequence of images to video
by 陈阳 04 Apr '18

04 Apr '18

Hi guys, I use ffmpeg to convert a sequence of images to a video, i find that after i feed first image to it and almost 6 seconds later ffmpeg output first video frame to me. I use command as follow: ffmpeg -f image2pipe -r 100 -i pipe:0 -f flv -r 100 -tune zerolatency -preset ultrafast -bufsize 2M -codec:v libx264 -codec:a libmp3lame -bf 0 -muxdelay 0.001 -s 478x850 -b:v 2M pipe:1 Is my options is right? Or others led to this result? How can i get first video frame quickly once i feed the first frame? By the way, i create a question in stack overflow, maybe you could answer my question at here(https://stackoverflow.com/q/49646564/8782964)

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Re: [FFmpeg-user] MP4 Can't play
by Carl Eugen Hoyos 04 Apr '18

04 Apr '18

2018-03-29 14:01 GMT+02:00, kun.gao(a)eeoa.com <kun.gao(a)eeoa.com>: > Hi: > > I just have one MP4 file. It can't play with ffplay.exe of version 3.2.4, > but it can with ffplay.exe of version 2.8.6. > > Can you please give some clue about this? > > File > URL:http://www.eeo.cn/upload/files/2018/201803/29/3c578a3089218f761740.mp4 This is now ticket #7123. Thank you, Carl Eugen

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Need Help!! WEBVTT & DVBSUB encoding options/metadata
by Eleftherios Antoniades 04 Apr '18

04 Apr '18

Hi Where can i find the options & metadata for the webvtt & dvbsub encoders Thank you!

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Unable to initialize SDL, over X11 for only root
by Jeff 03 Apr '18

03 Apr '18

Moritz / all, I thought we had all of our X11 issues solved with v3.4.0 of FFMpeg and SDL v2.0.7 (both built with standard configure/make/make install), but have since come across an unusual error. When launching *ffplay* as any normal user (X11 or direct terminal/desktop), I am able to play videos without a problem. However when running *ffplay* as the root user over X11 on the same files, I am getting met with the '*Unable to initialize SDL*' error. If I run that same file as the root user directly its root desktop (vice X11), it launches just fine. So it's only root over X11 (and possibly in VM vs. a pure hardware platform, but will need to confirm that). I came across this ( http://www.ffmpeg-archive.org/help-ffplay-Could-not-initialize-SDL-td467506…) thread/post form Moritz indicating there may be an issue using ffplay as root? In this particular case, there is a program daemon which is run as root that calls ffplay. This is why the call is being made by the root user. It seems something is different in the case of root over X11 vs. a direct terminal call from the root user's desktop, but I don't have the foggiest idea. Any thoughts would be greatly appreciated. Thanks, Jeff

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Reuse socket when close and reopening SDP
by sw 03 Apr '18

03 Apr '18

Is there a way to specify reuse_socket when opening an SDP? I have tried av_dict_set and av_opt_set prior to avformat_open_input. Neither work. If I close my connection with avformat_close_input and then try to reopen it, the socket gets a "bind failed". Any other suggestions how to work around this? Thanks, -- Sent from: http://www.ffmpeg-archive.org/

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Extract motion vectors and visualize as actual picture data
by Thomas Worth 03 Apr '18

03 Apr '18

Hey guys. I'd like to extract motion vectors out of a video file, but I don't want those little arrows superimposed over the picture as is done by the codecview=mv_type=fp video filter. I'd prefer to have the vectors output directly as either the luminance channel or one or more of the RGB channels. Is that possible with ffmpeg?

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Writing H.264 data to a file
by Austin Einter 03 Apr '18

03 Apr '18

In a call, I am receiving H.264 data in RTP packet. I need to write it to a mkv file to and then I should be able to play it using ffmpeg. It looks that I am always getting single NAL unit in RTP packet. My understanding is, I need to remove RTP packetization data (rfc 6184), and remove immediate next byte (F | NRI | TYPE), and then write remaining data to file prefixed with 0x00 0x00 00x1. After I prepare buffer, then I use av_write_xxx apis to write it using ffmpeg. The resultant file, I am not able to play. Kindly help me by pointing whats wrong here. -Austin

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