QVIDCAP(1)

✨ QVIDCAP ✨

okay bestie, gather round, because this is the manual page for qvidcap — a v4l2 video capture viewer, and it's literally the moment 💖

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🌸 SYNOPSIS 🌸

qvidcap [<options>]

💫 DESCRIPTION 💫

so the qvidcap tool is what you use to test video4linux capture devices — and she's flexible, because you can do it with a video device, a file, or over the network 🌈. This application can also serve as a generic video/TV viewer application, no big deal, just casually being a whole media player 💅

ngl it does NOT (yet) support compressed video streams other than MJPEG 😭 so keep that in mind bestie, that's a real limitation, fr fr

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🎀 OPTIONS 🎀

• -d, --device=<dev> — use device <dev> as the video device. And plot twist: if <dev> is a number, then /dev/video<dev> is used ✨
• -f, --file=<file> — read from the file <file> for the raw frame data 🍓
• -p, --port[=<port>] — listen for a network connection on the given port. The default port is 8362 👑
• -T, --tpg — use the test pattern generator. And if neither -d, -f nor -T is specified then use /dev/video0. so that's the fallback vibe 💜
• -c, --count=<cnt> — stop after <cnt> captured frames 🛑
• -b, --buffers=<bufs> — request <bufs> buffers (default 4) when streaming from a video device.
• -s, --single-step[=<frm>] — starting with frame <frm> (default 0), pause after displaying each frame until Space is pressed. one frame at a time, main character energy 👑
• -C, --colorspace=<c> — override colorspace. <c> can be one of the following colorspaces: smpte170m, smpte240m, rec709, 470m, 470bg, jpeg, srgb, oprgb, bt2020, dcip3 🌈
• -X, --xfer-func=<x> — override transfer function. <x> can be one of the following transfer functions: default, 709, srgb, oprgb, smpte240m, smpte2084, dcip3, none
• -Y, --ycbcr-enc=<y> — override Y'CbCr encoding. <y> can be one of the following Y'CbCr encodings: default, 601, 709, xv601, xv709, bt2020, bt2020c, smpte240m
• -Q, --quant=<q> — override quantization. <q> can be one of the following quantization methods: default, full-range, lim-range
• -P, --pixelformat=<p> — for video devices: set the format to this pixel format. For reading from a file: interpret the data using this pixel format setting. Ignored for other modes. Use -l to see the list of supported pixel formats 👀
• -l, --list-formats — display all supported formats 📋
• -h, --help — display this help message 🫶
• -t, --timings — report frame render timings ⏱️
• -v, --verbose — be more verbose. she talks more 💬
• -R, --raw — open device in raw mode
• --opengl — force openGL to display the video
• --opengles — force openGL ES to display the video

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🦋 the following options are ignored when capturing from a video device 🦋

• -W,--width=<width> — set width
• -H,--height=<height> — set frame (not field!) height ⚠️ note it's the FRAME height, not the field, don't get it twisted
• -A,--padding=<bytes> — set additional horizontal padding (after width)
• --fps=<fps> — set frames-per-second (default is 30)

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🧚 the following options are only valid when reading from a file 🧚

• -F, --field=<f> — override field setting. <f> can be one of the following field layouts: any, none, top, bottom, interlaced, seq_tb, seq_bt, alternate, interlaced_tb, interlaced_bt
• --no-loop — stop at the end of the file, don't loop back to the beginning. no infinite loop for you 🙈
• --from-frame=<frame> — start playing back the file at the given frame number (the first frame is frame 0). yes bestie, the first frame is frame 0, we're zero-indexed in this house 💅

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💜 the following options are specific to the test pattern generator 💜

• --list-patterns — list available patterns for use with --pattern
• --pattern=<pat> — choose output test pattern, the default is 0
• --square — show a square in the middle of the output test pattern ⬜
• --border — show a border around the pillar/letterboxed video
• --sav — insert an SAV code in every line
• --eav — insert an EAV code in every line
• --pixel-aspect=<aspect> — select a pixel aspect ratio, the default is to autodetect. <aspect> can be one of: square, ntsc, pal
• --video-aspect=<aspect> — select a video aspect ratio, the default is to use the frame ratio. <aspect> can be one of: 4 x3, 14x9, 16x9, anamorphic
• --alpha=<alpha-value> — value to use for the alpha component, range 0-255, the default is 0
• --alpha-red-only — only use the --alpha value for the red colors, for all others use 0 ❤️
• --rgb-lim-range — encode RGB values as limited [16-235] instead of full range
• --hor-speed=<speed> — choose speed for horizontal movement, the default is 0 and the range is [-3...3] ↔️
• --vert-speed=<speed> — choose speed for vertical movement, the default is 0 and the range is [-3...3] ↕️
• --perc-fill=<percentage> — percentage of the frame to actually fill. the default is 100%

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⭐ these options use the test pattern generator to test the OpenGL backend ⭐

• --test=<count> — test all formats, each test generates <count> frames 🧪
• --test-mask=<mask> — mask which tests are performed. <mask> is a bit mask with these values:

0x01: Mask iterating over pixel formats
0x02: Mask iterating over fields
0x04: Mask iterating over colorspaces
0x08: Mask iterating over transfer functions
0x10: Mask iterating over Y'CbCr encodings
0x20: Mask iterating over quantization ranges

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🔥 HOTKEYS 🔥

keyboard shortcuts, the whole point of existing tbh, let's go 🎹

• Q — quit application. bye bestie 👋
• P — cycle forwards through all the supported pixel formats. With Shift pressed: cycle backwards. With Ctrl pressed: restore the original pixel format. Only available with --file.
• I — cycle forwards through all the supported interlaced field settings. With Shift pressed: cycle backwards. With Ctrl pressed: restore the original interlaced field setting. Only available with --file.
• C — cycle forwards through all the supported colorspaces. With Shift pressed: cycle backwards. With Ctrl pressed: restore the original colorspace.
• X — cycle forwards through all the supported transfer functions. With Shift pressed: cycle backwards. With Ctrl pressed: restore the original transfer function.
• Y — cycle forwards through all the supported Y'CbCr encodings. With Shift pressed: cycle backwards. With Ctrl pressed: restore the original Y'CbCr encoding.
• H — cycle forwards through all the supported HSV encodings. With Shift pressed: cycle backwards. With Ctrl pressed: restore the original HSV encoding.
• R — cycle forwards through all the supported quantization ranges. With Shift pressed: cycle backwards. With Ctrl pressed: restore the original quantization range.
• Right-Click — open menu.
• Double left-click — toggle fullscreen on and off.
• F — toggle fullscreen on and off.
• ESC — exit fullscreen.
• Space — when in test mode (--test) pressing Space will skip to the next test. When single-stepping, continue to the next frame. When reading from a file, pause playback until the next press of Space.
• Backspace — when single-stepping, go back to the previous frame. ⏪
• Up — reduce the resolution by two pixels in height. Only available when "Override resolution" is enabled.
• Down — increase the resolution by two pixels in height. Only available when "Override resolution" is enabled.
• Left — reduce the resolution by two pixels in width. Only available when "Override resolution" is enabled.
• Right — increase the resolution by two pixels in width. Only available when "Override resolution" is enabled.

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💀 EXIT STATUS 💀

On success, it returns 0. Otherwise, it will return the number of errors. so if she returns 3 that's three whole errors bestie, count them 😭

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🐛 BUGS 🐛

Report bugs to Hans Verkuil <hverkuil@kernel.org> 📧

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and that's the whole thing, you ate that 💖

this gorgeous page came to you from v4l-utils 1.32.0, dated way back in June 2016 🎀 and yeah she's serving QVIDCAP(1) energy, no cap, periodt 💅✨