index.md (7196B)
1  2 3 blind is a collection of command line video editing utilities. 4 5 Video format 6 ------------ 7 blind uses a raw video format with a simple container. A file begins with an 8 plain-text line, containing the number of frames, the width, the height, and 9 the pixel format, all separated by a single regular blank space, without and 10 leading or tailing white space. After this line, which ends with an LF, there 11 is a NUL-byte followed by the 4 characters “uivf” (unportable, interim 12 video format). This head is followed by the video frame-by-frame with row-major 13 frames. Pixels are independently encoded, and are encoded unscaled CIE XYZ with 14 non-premultiplied alpha and without any transfer-function, with values stored 15 in native `double`s or optionally in native `float`s. These two configurations 16 are the only options, but the container format is designed so this can be 17 changed arbitrarily in the future. 18 19 FAQ 20 --- 21 22 ### Creating videos without graphics, are you insane? 23 24 Yes, but see the rationale below! 25 26 ### Doesn't raw video takes up a lot of space? 27 28 Yes it does, a 4-channel pixel encoded with `double` takes 32 bytes. A 29 1280-by-720 frame with this pixel format takes 29.4912 MB (SI), which means you 30 can only fit almost 3391 frames in 100 GB, which is about 113 seconds or 1:53 31 minutes with a framerate of 30 fps. Therefore, you probably do not want to 32 store anything in this format unless you know you have room for it, or if it is 33 very small segment of your video, which unfortunately becomes a bit of a problem 34 when reversing a video. However, when possible, feed the resulting video 35 directly to `blind-to-video` to convert it into a compressed, lossless video 36 format, if the video is not too large, you can choose to compress it with bzip2 37 instead. 38 39 ### For what kind of video editing is blind designed? 40 41 It is designed for composing new videos. It is not designed for making small 42 changes as this can probably be done faster with a graphical video editor or 43 with ffmpeg which would also be much faster. 44 45 ### Does it support farbfeld? 46 47 Of course. If you want to use farbfeld, you can use the `-f` flag for 48 `blind-to-image` and `blind-from-image`, this will cause the programs to 49 convert directly to or from farbfeld without using `convert(1)`. 50 51 ### Why doesn't blind uses encode pixels like farbfeld? 52 53 blind and farbfeld solve completely different problems. farbfeld solves to 54 problem of storing pictures in a simply way that can easily be viewed and 55 edited. blind does not try to solve the problem of storing videos, video 56 takes a lot of space and need compression designed especially for video or 57 three-dimensional raster images. Compressed video cannot be efficiently edited 58 because compression takes too long. Instead blind solves the problem of 59 efficiently processing video: thousands of pictures. Because blind doesn't try 60 to create a format for storing images, therefore it's format doesn't need to be 61 portable. Furthermore, due to legacy in television (namely, that of 62 black-and-white television), video formats do not store values in sRGB, but 63 rather in Y'UV, so there is next to no benefit to storing colours in sRGB. 64 65 ### Why doesn't blind use sRGB? 66 67 If I tell you I use CIE XYZ, you will only have two questions: “how are 68 values stored?” and “is Y scaled to [0, 100] or [0, 1]?” When I tell you 69 I use sRGB you have more questions: “do you support out-of-gamut colours?”, 70 “how are values stored?”, “which scale do you use?”, and “is the 71 transfer-function applied?” 72 73 CIE XYZ also has the advantage of having the brightness encoded in one of its 74 parameters, Y, and obtaining the chroma requires only simply conversion to a 75 non-standardise colour model that with the same Y-value. 76 77 ### Why does blind use CIE XYZ instead of CIE L\*a\*b\*? 78 79 Because CIE L\*a\*b\* is not linear, meaning that it requires unnecessary 80 calculations when working with the colours. 81 82 ### Why does blind use CIE XYZ instead of Y'UV or YUV? 83 84 Y'UV has good performance for converting to sRGB and is has good subsampling 85 quality, but it is not a good for editing. Y'UV is non-linear, so it has the 86 same disadvantages as CIE L\*a\*b\*. Y'UV does not have its transfer-function 87 applied directly to it's parameters, instead it is a linear transformation if 88 the sRGB with its transfer-function applied. This means that no performance is 89 gained during conversion to or from cooked video formats by using YUV. CIE XYZ 90 also has the advantage that it is well-known and has a one-step conversion to 91 almost all colour models. It also have the advantages that it's parameters are 92 named X, Y, Z, which makes it very easy to choose parameter when storing points 93 instead of colours in a video. 94 95 ### Doesn't blind have any audio support? 96 97 No, it is not clear that there is actually a need for this. There are good 98 tools for editing audio, and ffmpeg can be used to extract the audio 99 streams from a video or add it to a video. 100 101 ### Is it really feasible to edit video without a GUI? 102 103 Depends on what you are doing. Many things can be done without a GUI, and 104 some thing are easier to do without one. If you find that you need GUI it 105 possible to combine blind with a graphical editor. Furthermore, blind could be 106 used in by a graphical editor if one were to write a graphical editor to use 107 blind. 108 109 Rationale 110 --------- 111 * It's source control friendly and it's easy for a user to resolve merge 112 conflicts and identify changes. 113 * Rendering can take a very long time. With this approach, the user can use 114 Make to only rerender parts that have been changed. 115 * It's possible to distribute the rendering to multiple computers, without any 116 built in functionality for this, for example using a distributed Make. 117 * Parallelism is added for free. 118 * No room for buggy GUIs, which currently is a problem with the large video 119 editors for Linux. 120 * Less chance that the user makes a change by mistake without noticing it, such 121 as moving a clip in the editor by mistake instead of for example resizing. 122 * Even old, crappy computers can be used for large projects. 123 * Very easy to utilise command line image editors for modify frames, or to add 124 your own tools for custom effects. 125 126 Development 127 ----------- 128 You can browse its [source code repository](//git.suckless.org/blind) or get a 129 copy using git with the following command: 130 131 git clone https://git.suckless.org/blind 132 133 Download 134 -------- 135 * [blind-1.0](//dl.suckless.org/tools/blind-1.0.tar.gz) (2017-01-22) 136 * [blind-1.1](//dl.suckless.org/tools/blind-1.1.tar.gz) (2017-05-06) 137 138 Also make sure to check your package manager. The following distributions 139 provide packages: 140 141 * [Alpine Linux](https://pkgs.alpinelinux.org/package/edge/testing/x86_64/blind) 142 * [Arch Linux (AUR)](https://aur.archlinux.org/packages/blind/) 143 * [Arch Linux (AUR), git version](https://aur.archlinux.org/packages/blind-git/) 144 145 Dependencies 146 ------------ 147 * [ffmpeg](https://www.ffmpeg.org/) - for converting from or to other video 148 formats. 149 * [imagemagick](https://www.imagemagick.org/) - for converting regular images 150 to frames. 151 152 Links 153 ----- 154 * [Video tutorials](https://www.youtube.com/channel/UCg_nJOURt3guLtp4dQLIvQw) 155 156 157 Author 158 ------ 159 * Mattias Andrée (maandree@kth.se)