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public:it:ffmpeg [2022/03/19 21:03] – [Non-monotonous DTS in output stream] philpublic:it:ffmpeg [Unknown date] (current) – removed - external edit (Unknown date) 127.0.0.1
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-====== ffmepg ====== 
- 
-  * [[https://ffmpeg.org/ffmpeg.html| man page ]] 
-  * [[https://ffmpeg.org/ffmpeg-all.html|All Options]] 
- 
-  * [[https://docs.nvidia.com/video-technologies/video-codec-sdk/ffmpeg-with-nvidia-gpu/|ffmpeg with Nvidia GPU]] 
- 
-  * https://www.ramugedia.com/how-encode-decode-hevc-h-265-by-intel-quick-sync-video-hw--qsv- 
-  * https://trac.ffmpeg.org/wiki/Hardware/QuickSync 
-  * https://gist.github.com/andrearug/ee461152acfbbd3f52b3bb9ffb55b6b8 
-  *  
-  * https://geoffruddock.com/bulk-compress-videos-x265-with-ffmpeg/ 
-  * https://slhck.info/video/2017/02/24/crf-guide.html 
-  * https://netflixtechblog.com/a-large-scale-comparison-of-x264-x265-and-libvpx-a-sneak-peek-2e81e88f8b0f 
-  * https://www.youtube.com/watch?v=wi1BefrfTos 
-  * https://video.stackexchange.com/questions/14907/how-to-downsample-4k-to-1080p-using-ffmpeg-while-maintaining-the-quality 
- 
- 
-===== Build ===== 
- 
-  * https://github.com/markus-perl/ffmpeg-build-script 
- 
-=====  Manipulating audio channels  ===== 
- 
-  * https://trac.ffmpeg.org/wiki/AudioChannelManipulation#a5.1stereo 
-  * https://superuser.com/a/1616102 
-  * https://datatracker.ietf.org/doc/html/rfc7845#section-5.1.1.5 
- 
-==== 5.1 Surround downmix to stereo ==== 
-FL, FC, FR, BL, BR, LFE -> FL, FR 
-<code> 
--ac 2 \ 
--af "pan=stereo|FL = 0.374107*FC + 0.529067*FL + 0.458186*BL + 0.264534*BR + 0.374107*LFE |FR = 0.374107*FC + 0.529067*FR + 0.458186*BR + 0.264534*BL + 0.374107*LFE" \ 
-</code> 
- 
- 
-==== 7.1 downmix to stereo ==== 
-FL, FC, FR, SL, SR, BL, BR, LFE -> FL, FR 
-<code> 
--ac 2 \ 
--af "pan=stereo|FL = 0.274804*FC + 0.388631*FL + 0.336565*SL + 0.194316*SR + 0.336565*BL + 0.194316*BR + 0.274804*LFE | FR = 0.274804*FC + 0.388631*FR + 0.336565*SR + 0.194316*SL + 0.336565*BR + 0.194316*BL + 0.274804*LFE" \ 
-</code> 
- 
- 
-==== 6.1 downmix to stereo==== 
-FL, FC, FR, SL, SR, BC, LFE -> FL, FR 
-<code> 
--ac 2 \ 
--af "pan=stereo|FL = 0.321953*FC + 0.455310*FL + 0.394310*SL + 0.227655*SR + 278819*BC + 0.321953*LFE | FR = 0.321953*FC + 0.455310*FR + 0.394310*SR + 0.227655*SL + 278819*BC + 0.321953*LFE" \ 
-</code> 
- 
-==== 5.0 downmix to stereo ==== 
-FL, FC, FR, BL, BR -> FL, FR 
-<code> 
--ac 2 \ 
--af "pan=stereo|FL = 0.460186*FC + 0.650802*FL + 0.563611*BL + 0.325401*BR | FR = 0.460186*FC + 0.650802*FR + 0.563611*BR + 0.325401*BL" \ 
-</code> 
- 
-==== Quadraphonic Channel downmix to stereo==== 
-FL, FR, BL, BR -> FL, FR 
-<code> 
--ac 2 \ 
--af "pan=stereo|FL = 0.422650*FL + 0.366025*BL + 0.211325*BR | FR = 0.422650*FR + 0.366025*BR + 0.211325*BL" \ 
-</code> 
- 
-==== Linear Surround Channel downmix to stereo ==== 
-FL, FC, FR -> FL, FR 
-<code> 
--ac 2 \ 
--af "pan=stereo|FL = 0.414214*FC + 0.585786*FL | FR = 0.414214*FC + 0.585786*FR" \ 
-</code> 
- 
-===== Scaling ===== 
- 
-==== QSV Scale to 1080p ==== 
- 
-Quality with QSV as not good at all, though this could have been my fault. 
-<code> 
-ffmpeg \ 
-  -y \ 
-  -hwaccel qsv \ 
-  -qsv_device /dev/dri/card0 \ 
-  -c:v hevc_qsv \ 
-  -i input.mkv \ 
-  -c:v hevc_qsv \ 
-  -vf 'scale_qsv=w=1920' \ 
-  -preset slow \ 
-  -global_quality 25 \ 
-  -c:a copy \ 
-  -c:s copy \ 
-  output.mkv 
-</code> 
- 
- 
-==== 4k to 1080p ==== 
- 
-  * libx264 
-  * libx265 
- 
-<code> 
-ffmpeg \ 
-  -i MyMovie_4K.mkv \ 
-  -vf scale=1920:-1 \ 
-  -c:v libx265 \ 
-  -preset veryslow \ 
-  -c:a copy \ 
-  MyMovie_1080p.mkv 
-</code> 
- 
-Not sure if these are necessary. 
-<code> 
--crf 28 
-</code> 
- 
- 
-===== Subtitles ===== 
- 
-==== MKV Embed soft subtitles ==== 
-  * [[https://gist.github.com/kurlov/32cbe841ea9d2b299e15297e54ae8971]] 
-<code> 
-ffmpeg \ 
-  -i in.mkv \ 
-  -f srt \ 
-  -i in.srt \ 
-  -map 0:0 \ 
-  -map 0:1 \ 
-  -map 1:0 \ 
-  -c:v copy \ 
-  -c:a copy \ 
-  -c:s srt \ 
-  out.mkv 
-</code> 
- 
-==== MKV hardcode subtitles ==== 
- 
-http://diantokam.blogspot.com/2016/12/adding-subtitle-and-scaling-film-using.html 
- 
-<code> 
-ffmpeg \ 
-  -i "input.mkv" \ 
-  -vf subtitles=fullsubs.srt \ 
-  "output.mkv" 
-</code> 
- 
- 
-==== MKV to MP4 hardcode subtitles and downmix 5.1 to stereo ==== 
- 
-<code> 
-  # export english subs 
-  ffmpeg \ 
-    -y \ 
-    -i "./${name}" \ 
-    -map 0:s:0 \ 
-    eng.srt 
- 
-  # create a version with hardsubs 
-  # si=0 
-  ffmpeg \ 
-    -y \ 
-    -i "./${name}" \ 
-    -vf subtitles="${name}":si=0 \ 
-    -ac 2 \ 
-    -af "pan=stereo|FL = 0.374107*FC + 0.529067*FL + 0.458186*BL + 0.264534*BR + 0.374107*LFE |FR = 0.374107*FC + 0.529067*FR + 0.458186*BR + 0.264534*BL + 0.374107*LFE" \ 
-    -c:a aac \ 
-    "${name}-hardsubs.mp4" 
- 
-</code> 
-==== Delay subtitle by 1 second ==== 
- 
-<code> 
-ffmpeg \ 
-  -itsoffset -1 \ 
-  -i full8.srt \ 
-  -c copy \ 
-  full8_delayed.srt 
-</code> 
- 
- 
- 
- 
- 
- 
-====== Video Streaming ====== 
- 
-https://hub.docker.com/r/tiangolo/nginx-rtmp 
-https://www.nginx.com/blog/video-streaming-for-remote-learning-with-nginx/ 
- 
- 
-  ffmpeg -h encoder=hevc_qsv 
- 
- 
-====== Clips ====== 
- 
- 
-<code> 
-ffmpeg \ 
-  -i  input.mkv \ 
-  -ss 29:36 \ 
-  -to 29:50 \ 
-  -c:v copy \ 
-  -c:a aac \ 
-  output.mp4 
-</code> 
- 
- 
- 
-====== h264 to hevc using nvenc ====== 
- 
-  - Install docker 
-  - Install nvidia docker: https://docs.nvidia.com/datacenter/cloud-native/container-toolkit/install-guide.html 
-  - Docker ffmpeg image: https://hub.docker.com/r/jrottenberg/ffmpeg 
- 
-<code> 
-docker run \ 
-  -v $(pwd):$(pwd) \ 
-  -w $(pwd) \ 
-  --runtime=nvidia jrottenberg/ffmpeg:4.1-nvidia \ 
-  -hwaccel cuvid \ 
-  -c:v h264_cuvid \ 
-  -i input.mkv \ 
-  -c:v hevc_nvenc \ 
-  -c:a copy \ 
-  -c:s copy \ 
-  -preset slow \ 
-  output_hevc.mkv 
-</code> 
- 
- 
-====== Errors ====== 
- 
-===== Error creating a NVDEC decoder ===== 
- 
-<code> 
-[h264 @ 0x56028de15ec0] Error creating a NVDEC decoder: 1 
-[h264 @ 0x56028de15ec0] Using more than 32 (34) decode surfaces might cause nvdec to fail. 
-[h264 @ 0x56028de15ec0] Try lowering the amount of threads. Using 16 right now. 
-[h264 @ 0x56028de15ec0] Failed setup for format cuda: hwaccel initialisation returned error. 
-</code> 
- 
-  * https://ffmpeg.org/pipermail/ffmpeg-user/2019-June/044610.html 
- 
-> Note that cuda hwaccel is an alias to the newer nvdec implementation, and to my knowledge, has no way of setting up decoder surface limits. 
->  
-> Here's a workaround you can try: 
- 
-<code> 
-ffmpeg \ 
-  -threads 4 \ 
-  -hide_banner \ 
-  -c:v h264_cuvid \ 
-  -surfaces 8 \ 
-  -nostats \ 
-  -i rtmp://<ip>:<port>/myapp/mystream \ 
-  -filter_complex [0]fps=fps=1[s0] \ 
-  -map [s0] \ 
-  -f rawvideo \ 
-  -pix_fmt rgb24 pipe 
-</code> 
- 
-> Two changes: 
-> 
-> 1: Call up the h264_cuvid decoder directly, and apply a surface limit count of 8. This should be adequate. 
-> 2: Limit the thread count. 
- 
- 
-===== Non-monotonous DTS in output stream ===== 
- 
-  * https://stackoverflow.com/a/48874015 
- 
-<code> 
-[matroska @ 0x55a1a3738340] Non-monotonous DTS in output stream 0:1; previous: 490791, current: 490731; changing to 490791. This may result in incorrect timestamps in the output file. 
-</code> 
- 
-Try ''%%-use_wallclock_as_timestamps 1%%'' and ''%%-fflags +genpts%%'' 
  
public/it/ffmpeg.1647741817.txt.gz · Last modified: 2022/03/19 21:03 by phil

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