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• ffmpeg command for faster encoding at a decent bitrate with smaller file size

  28 juillet 2023, par Blair Holmes

  I'm currently using an implementation of ffmpeg on my android app. I'm allowing users to take short videos within my app and then when they upload them to the server, I'm crunching them down with ffmpeg to decrease file size so they're not passing huge amounts of data over the wire.

  



  the problem is, it's taking forever to encode the videos on the android device. These videos usually aren't longer than 45 seconds and can take 20 minutes to encode. I've done some playing around with different switches / parameters on the ffmpeg command line and I now have it at a more comfortable time, but the file sizes are significantly bigger. I'm just not sure what codec I should use (fastest encoding but with decent quality output), how ffmpeg handles changing size (aspect ratio) in terms of speed of encoding etc.

  



  Here are the two commands I've been using. This first one outputs the file size / quality that I want, but it just takes way too long to encode, not to mention it makes my device get really hot while it's encoding for so long :

  



  ffmpeg -i input.mp4 -b:v 1024k -c:a copy -vf scale=960:540 output.mp4


  



  I've tweaked the bitrate some on that as well as changed the scale to a smaller size, but I don't want to have to make the videos really small (in terms of scale) to accomplish a faster encoding. this second command goes a lot faster but makes the file size significantly bigger :

  



  ffmpeg -i input.mp4 -vcodec libx264 -preset fast -c:a copy -s 960x540 output.mp4


  



  I'd like to find a happy medium (smaller file size but faster encoding) keeping the video scale size close to the original. ffmpeg just has so many different parameters / switches that it's difficult to wrap my head around what I should be doing.

  



  EDIT : adding ffmpeg output.

  



  ffmpeg -i input.mp4 -vcodec libx264 -crf 30 -preset veryfast -c:a copy -s 960x540 output.mp4

  



      09-13 11:06:28.330 10881-10881/someapp D/home: ffmpeg version n3.0.1 Copyright (c) 2000-2016 the FFmpeg developers
09-13 11:06:28.330 10881-10881/someapp D/home:   built with gcc 4.8 (GCC)
09-13 11:06:28.331 10881-10881/someapp D/home:   configuration: --target-os=linux --cross-prefix=/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/bin/arm-linux-androideabi- --arch=arm --cpu=cortex-a8 --enable-runtime-cpudetect --sysroot=/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/sysroot --enable-pic --enable-libx264 --enable-libass --enable-libfreetype --enable-libfribidi --enable-libmp3lame --enable-fontconfig --enable-pthreads --disable-debug --disable-ffserver --enable-version3 --enable-hardcoded-tables --disable-ffplay --disable-ffprobe --enable-gpl --enable-yasm --disable-doc --disable-shared --enable-static --pkg-config=/home/vagrant/SourceCode/ffmpeg-android/ffmpeg-pkg-config --prefix=/home/vagrant/SourceCode/ffmpeg-android/build/armeabi-v7a --extra-cflags='-I/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/include -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fno-strict-overflow -fstack-protector-all' --extra-ldflags='-L/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/lib -Wl,-z,relro -Wl,-z,now -pie' --extra-libs='-lpng -lexpat -lm' --extra-cxxflags=
09-13 11:06:28.331 10881-10881/someapp D/home:   libavutil      55. 17.103 / 55. 17.103
09-13 11:06:28.331 10881-10881/someapp D/home:   libavcodec     57. 24.102 / 57. 24.102
09-13 11:06:28.331 10881-10881/someapp D/home:   libavformat    57. 25.100 / 57. 25.100
09-13 11:06:28.331 10881-10881/someapp D/home:   libavdevice    57.  0.101 / 57.  0.101
09-13 11:06:28.331 10881-10881/someapp D/home:   libavfilter     6. 31.100 /  6. 31.100
09-13 11:06:28.331 10881-10881/someapp D/home:   libswscale      4.  0.100 /  4.  0.100
09-13 11:06:28.331 10881-10881/someapp D/home:   libswresample   2.  0.101 /  2.  0.101
09-13 11:06:28.331 10881-10881/someapp D/home:   libpostproc    54.  0.100 / 54.  0.100
09-13 11:06:28.430 10881-10881/someapp D/home: Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/storage/emulated/0/ExpeditionSpot/Videos/20160913110411.mp4':
09-13 11:06:28.430 10881-10881/someapp D/home:   Metadata:
09-13 11:06:28.430 10881-10881/someapp D/home:     major_brand     : mp42
09-13 11:06:28.430 10881-10881/someapp D/home:     minor_version   : 0
09-13 11:06:28.430 10881-10881/someapp D/home:     compatible_brands: isommp42
09-13 11:06:28.430 10881-10881/someapp D/home:     creation_time   : 2016-09-13 17:04:33
09-13 11:06:28.430 10881-10881/someapp D/home:     com.android.version: 6.0.1
09-13 11:06:28.430 10881-10881/someapp D/home:   Duration: 00:00:19.41, start: 0.000000, bitrate: 20222 kb/s
09-13 11:06:28.430 10881-10881/someapp D/home:     Stream #0:0(eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p, 1920x1080, 19963 kb/s, SAR 1:1 DAR 16:9, 30.03 fps, 30 tbr, 90k tbn, 180k tbc (default)
09-13 11:06:28.430 10881-10881/someapp D/home:     Metadata:
09-13 11:06:28.430 10881-10881/someapp D/home:       creation_time   : 2016-09-13 17:04:33
09-13 11:06:28.430 10881-10881/someapp D/home:       handler_name    : VideoHandle
09-13 11:06:28.431 10881-10881/someapp D/home:     Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 96 kb/s (default)
09-13 11:06:28.431 10881-10881/someapp D/home:     Metadata:
09-13 11:06:28.431 10881-10881/someapp D/home:       creation_time   : 2016-09-13 17:04:33
09-13 11:06:28.431 10881-10881/someapp D/home:       handler_name    : SoundHandle
09-13 11:06:28.448 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] using SAR=1/1
09-13 11:06:28.448 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] using cpu capabilities: none!
09-13 11:06:28.516 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] profile High, level 3.1
09-13 11:06:28.516 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] 264 - core 148 - H.264/MPEG-4 AVC codec - Copyleft 2003-2015 - http://www.videolan.org/x264.html - options: cabac=1 ref=1 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=2 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=12 lookahead_threads=4 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=1 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=10 rc=crf mbtree=1 crf=27.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
09-13 11:06:28.532 10881-10881/someapp D/home: Output #0, mp4, to '/storage/emulated/0/ExpeditionSpot/.tmp/small-20160913110411.mp4':
09-13 11:06:28.532 10881-10881/someapp D/home:   Metadata:
09-13 11:06:28.532 10881-10881/someapp D/home:     major_brand     : mp42
09-13 11:06:28.533 10881-10881/someapp D/home:     minor_version   : 0
09-13 11:06:28.533 10881-10881/someapp D/home:     compatible_brands: isommp42
09-13 11:06:28.533 10881-10881/someapp D/home:     com.android.version: 6.0.1
09-13 11:06:28.533 10881-10881/someapp D/home:     encoder         : Lavf57.25.100
09-13 11:06:28.533 10881-10881/someapp D/home:     Stream #0:0(eng): Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 960x540 [SAR 1:1 DAR 16:9], q=-1--1, 30 fps, 15360 tbn, 30 tbc (default)
09-13 11:06:28.533 10881-10881/someapp D/home:     Metadata:
09-13 11:06:28.533 10881-10881/someapp D/home:       creation_time   : 2016-09-13 17:04:33
09-13 11:06:28.533 10881-10881/someapp D/home:       handler_name    : VideoHandle
09-13 11:06:28.533 10881-10881/someapp D/home:       encoder         : Lavc57.24.102 libx264
09-13 11:06:28.533 10881-10881/someapp D/home:     Side data:
09-13 11:06:28.533 10881-10881/someapp D/home:       unknown side data type 10 (24 bytes)
09-13 11:06:28.533 10881-10881/someapp D/home:     Stream #0:1(eng): Audio: aac (LC) ([64][0][0][0] / 0x0040), 48000 Hz, stereo, 96 kb/s (default)
09-13 11:06:28.533 10881-10881/someapp D/home:     Metadata:
09-13 11:06:28.533 10881-10881/someapp D/home:       creation_time   : 2016-09-13 17:04:33
09-13 11:06:28.533 10881-10881/someapp D/home:       handler_name    : SoundHandle
09-13 11:06:28.533 10881-10881/someapp D/home: Stream mapping:
09-13 11:06:28.533 10881-10881/someapp D/home:   Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
09-13 11:06:28.533 10881-10881/someapp D/home:   Stream #0:1 -> #0:1 (copy)
09-13 11:06:28.533 10881-10881/someapp D/home: Press [q] to stop, [?] for help
09-13 11:06:29.102 10881-10881/someapp D/home: frame=    7 fps=0.0 q=0.0 size=       0kB time=00:00:01.04 bitrate=   0.4kbits/s speed=2.08x    
09-13 11:06:29.699 10881-10881/someapp D/home: frame=   16 fps= 15 q=0.0 size=       0kB time=00:00:01.04 bitrate=   0.4kbits/s speed=0.998x    
....
09-13 11:07:12.674 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] frame I:3     Avg QP:26.83  size: 21896
09-13 11:07:12.674 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] frame P:279   Avg QP:28.76  size:  5859
09-13 11:07:12.674 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] frame B:296   Avg QP:29.93  size:   863
09-13 11:07:12.674 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] consecutive B-frames: 18.3% 32.2% 23.9% 25.6%
09-13 11:07:12.674 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] mb I  I16..4: 16.9% 54.2% 28.9%
09-13 11:07:12.674 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] mb P  I16..4:  7.7%  9.1%  0.4%  P16..4: 27.5% 11.1%  4.0%  0.0%  0.0%    skip:40.1%
09-13 11:07:12.674 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] mb B  I16..4:  0.8%  0.6%  0.0%  B16..8: 10.9%  2.4%  0.1%  direct: 1.8%  skip:83.5%  L0:35.8% L1:54.2% BI:10.0%
09-13 11:07:12.675 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] 8x8 transform intra:52.0% inter:41.3%
09-13 11:07:12.675 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] coded y,uvDC,uvAC intra: 28.9% 26.0% 2.1% inter: 6.4% 5.0% 0.0%
09-13 11:07:12.675 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] i16 v,h,dc,p: 57% 20% 17%  6%
09-13 11:07:12.675 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 33% 23% 34%  1%  2%  1%  3%  2%  2%
09-13 11:07:12.675 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 36% 21% 17%  2%  7%  4%  6%  4%  4%
09-13 11:07:12.675 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] i8c dc,h,v,p: 59% 16% 23%  2%
09-13 11:07:12.675 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] Weighted P-Frames: Y:16.8% UV:4.7%
09-13 11:07:12.675 10881-10881/someapp D/home: [libx264 @ 0xf71c4400] kb/s:812.09


  


• Ffmpeg Command to capture video from Decklink 4k Extreme in Ubuntu Linux

  24 septembre 2016, par George.Ef

  I am trying to capture a video using ffmpeg, from the HDMI input port of the Blackmagic DeckLink 4K Extreme capture card in Ubuntu Linux.

  As per the ffmpeg Documentation I have tried the following :

  ffmpeg -f decklink -video_input 'hdmi' -i 'DeckLink 4K Extreme (1)@14' -acodec copy -vcodec copy ~/testCapture/card1_f14_hdmi.avi

  but no matter what I do I always get this picture as a video
  

  My ffmpeg version is :

  ffmpeg version git-2016-08-15-4899953 Copyright (c) 2000-2016 the FFmpeg developers
  
  built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  
  configuration: --prefix=/root/ffmpeg_build --pkg-config-flags=--static 
  
  --extra-cflags=-I/root/ffmpeg_build/include 
  
  --extra-ldflags=-L/root/ffmpeg_build/lib 
  
  --bindir=/root/bin --enable-gpl --enable-libass --enable-libfdk-aac 
  
  --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora 
  
  --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 
  
  --enable-decklink 
  
  --extra-cflags=-I/root/decklinkSDK/Blackmagic_DeckLink_SDK/Linux/include
  
  --extra-ldflags=-L/root/decklinkSDK/Blackmagic_DeckLink_SDK/Linux/include
  
  --enable-nonfree
  
  libavutil      55. 28.100 / 55. 28.100
  
  libavcodec     57. 51.102 / 57. 51.102
  
  libavformat    57. 46.101 / 57. 46.101
  
  libavdevice    57.  0.102 / 57.  0.102
  
  libavfilter     6. 51.100 /  6. 51.100
  
  libswscale      4.  1.100 /  4.  1.100
  
  libswresample   2.  1.100 /  2.  1.100
  
  libpostproc    54.  0.100 / 54.  0.100

  I have two of these cards as per the following :

  ffmpeg -f decklink -list_devices 1 -i dummy
  
  .....
  
  [decklink @ 0x2e9e440] Blackmagic DeckLink devices:
  
  [decklink @ 0x2e9e440]    'DeckLink 4K Extreme (1)'
  
  [decklink @ 0x2e9e440]    'DeckLink 4K Extreme (2)'

  I am able to get a list of the supported formats with the following :

  ffmpeg -f decklink -list_formats 1 -i 'DeckLink 4K Extreme (1)'
  
  ...
  
  [decklink @ 0x36e2440] Supported formats for 'DeckLink 4K Extreme (1)':
  
  [decklink @ 0x36e2440]    1   720x486 at 30000/1001 fps (interlaced, lower field first)
  
  [decklink @ 0x36e2440]    2   720x576 at 25000/1000 fps (interlaced, upper field first)
  
  [decklink @ 0x36e2440]    3   1920x1080 at 24000/1001 fps
  
  [decklink @ 0x36e2440]    4   1920x1080 at 24000/1000 fps
  
  [decklink @ 0x36e2440]    5   1920x1080 at 25000/1000 fps
  
  [decklink @ 0x36e2440]    6   1920x1080 at 30000/1001 fps
  
  [decklink @ 0x36e2440]    7   1920x1080 at 30000/1000 fps
  
  [decklink @ 0x36e2440]    8   1920x1080 at 25000/1000 fps (interlaced, upper field first)
  
  [decklink @ 0x36e2440]    9   1920x1080 at 30000/1001 fps (interlaced, upper field first)
  
  [decklink @ 0x36e2440]    10  1920x1080 at 30000/1000 fps (interlaced, upper field first)
  
  [decklink @ 0x36e2440]    11  1920x1080 at 50000/1000 fps
  
  [decklink @ 0x36e2440]    12  1920x1080 at 60000/1001 fps
  
  [decklink @ 0x36e2440]    13  1920x1080 at 60000/1000 fps
  
  [decklink @ 0x36e2440]    14  1280x720 at 50000/1000 fps
  
  [decklink @ 0x36e2440]    15  1280x720 at 60000/1001 fps
  
  [decklink @ 0x36e2440]    16  1280x720 at 60000/1000 fps
  
  ...
  
  DeckLink 4K Extreme (1): Immediate exit requested

  What should I use with ffmpeg in order to capture an HD video with sound from the HDMI port ?

• Translating Return To Ringworld

  17 août 2016, par Multimedia Mike — Game Hacking

  As indicated in my previous post, the Translator has expressed interest in applying his hobby towards another DOS adventure game from the mid 1990s : Return to Ringworld (henceforth R2RW) by Tsunami Media. This represents significantly more work than the previous outing, Phantasmagoria.

  
  
  Return to Ringworld Title Screen
  

  I have been largely successful thus far in crafting translation tools. I have pushed the fruits of these labors to a Github repository named improved-spoon (named using Github’s random name generator because I wanted something more interesting than ‘game-hacking-tools’).

  Further, I have recorded everything I have learned about the game’s resource format (named RLB) at the XentaxWiki.

  New Challenges
  The previous project mostly involved scribbling subtitle text on an endless series of video files by leveraging a separate software library which took care of rendering fonts. In contrast, R2RW has at least 30k words of English text contained in various blocks which require translation. Further, the game encodes its own fonts (9 of them) which stubbornly refuse to be useful for rendering text in nearly any other language.

  Thus, the immediate 2 challenges are :
  

  1. Translating volumes of text to Spanish
  2. Expanding the fonts to represent Spanish characters

  Normally, “figuring out the file format data structures involved” is on the list as well. Thankfully, understanding the formats is not a huge challenge since the folks at the ScummVM project already did all the heavy lifting of reverse engineering the file formats.

  The Pitch
  Here was the plan :

  • Create a tool that can dump out the interesting data from the game’s master resource file.
  • Create a tool that can perform the elaborate file copy described in the previous post. The new file should be bit for bit compatible with the original file.
  • Modify the rewriting tool to repack some modified strings into the new resource file.
  • Unpack the fonts and figure out a way to add new characters.
  • Repack the new fonts into the resource file.
  • Repack message strings with Spanish characters.

  Showing The Work : Modifying Strings
  First, I created the tool to unpack blocks of message string resources. I elected to dump the strings to disk as JSON data since it’s easy to write and read JSON using Python, and it’s quick to check if any mistakes have crept in.

  The next step is to find a string to focus on. So I started the game and looked for the first string I could trigger :

  
  
  

  This shows up in the JSON string dump as :

    
      "Spanish" : " !0205Your quarters on the Lance of Truth are spartan, in accord with your mercenary lifestyle.",
      "English" : " !0205Your quarters on the Lance of Truth are spartan, in accord with your mercenary lifestyle."
    ,
  

  As you can see, many of the strings are encoded with an ID key as part of the string which should probably be left unmodified. I changed the Spanish string :

    
      "Spanish" : " !0205Hey, is this thing on ?",
      "English" : " !0205Your quarters on the Lance of Truth are spartan, in accord with your mercenary lifestyle."
    ,
  

  And then I wrote the repacking tool to substitute this message block for the original one. Look ! The engine liked it !

  
  
  

  Little steps, little steps.

  Showing The Work : Modifying Fonts
  The next little step is to find a place to put the new characters. First, a problem definition : The immediate goal is to translate the game into Spanish. The current fonts encoded in the game resource only support 128 characters, corresponding to 7-bit ASCII. In order to properly express Spanish, 16 new characters are required : á, é, í, ó, ú, ü, ñ (each in upper and lower case for a total of 14 characters) as well as the inverted punctuation symbols : ¿, ¡.

  Again, ScummVM already documents (via code) the font coding format. So I quickly determined that each of the 9 fonts is comprised of 128 individual bitmaps with either 1 or 2 bits per pixel. I wrote a tool to unpack each character into an individual portable grey map (PGM) image. These can be edited with graphics editors or with text editors since they are just text files.

  Where to put the 16 new Spanish characters ? ASCII characters 1-31 are non-printable, so my first theory was that these characters would be empty and could be repurposed. However, after dumping and inspecting, I learned that they represent the same set of characters as seen in DOS Code Page 437. So that’s a no-go (so I assumed ; I didn’t check if any existing strings leveraged those characters).

  My next plan was hope that I could extend the font beyond index 127 and use positions 128-143. This worked superbly. This is the new example string :

    
      "Spanish" : " !0205¿Ves esto ? ¡La puntuacion se hace girar !",
      "English" : " !0205Your quarters on the Lance of Truth are spartan, in accord with your mercenary lifestyle."
    ,
  

  Fortunately, JSON understands UTF-8 and after mapping the 16 necessary characters down to the numeric range of 128-143, I repacked the new fonts and the new string :

  
  
  Translation : “See this ? The punctuation is rotated !”
  

  Another victory. Notice that there are no diacritics in this string. None are required for this translation (according to Google Translate). But adding the diacritics to the 14 characters isn’t my department. My tool does help by prepopulating [aeiounAEIOUN] into the right positions to make editing easier for the Translator. But the tool does make the effort to rotate the punctuation since that is easy to automate.

  Next Steps and Residual Weirdness
  There is another method for storing ASCII text inside the R2RW resource called strip resources. These store conversation scripts. There are plenty of fields in the data structures that I don’t fully understand. So, following the lessons I learned from my previous translation outing, I was determined to modify as little as possible. This means copying over most of the original data structures intact, but changing the field representing the relative offset that points to the corresponding string. This works well since the strings are invariably stored NULL-terminated in a concatenated manner.

  I wanted to document for the record that the format that R2RW uses has some weirdness in they way it handles residual bytes in a resource. The variant of the resource format that R2RW uses requires every block to be aligned on a 16-byte boundary. If there is space between the logical end of the resource and the start of the next resource, there are random bytes in that space. This leads me to believe that these bytes were originally recorded from stale/uninitialized memory. This frustrates me because when I write the initial file copy tool which unpacks and repacks each block, I want the new file to be identical to the original. However, these apparent nonsense bytes at the end thwart that effort.

  But leaving those bytes as 0 produces an acceptable resource file.

  Text On Static Images
  There is one last resource type we are working on translating. There are various bits of text that are rendered as images. For example, from the intro :

  
  
  

  It’s possible to locate and extract the exact image that is overlaid on this scene, though without the colors :

  
  
  

  The palettes are stored in a separate resource type. So it seems the challenge is to figure out the palette in use for these frames and render a transparent image that uses the same palette, then repack the new text-image into the new resource file.

  The post Translating Return To Ringworld first appeared on Breaking Eggs And Making Omelettes.