MultimediaWiki - User contributions [en]

Talk:Microsoft IMA ADPCM

2022-03-20T16:02:26Z

Cecodere:

Maybe I am wrong, but according to the Microsoft WAVE AVI Codec registry on the IETF, the Audio ID here should be 0x0002 and not 0x0011, where 0x0011 seems to point to Intel's DVI ADPCM instead. Please check [https://www.iana.org/assignments/wave-avi-codec-registry/wave-avi-codec-registry.xml] for more information. Furthermore, the Quicktime ID should be MS$0011.

Talk:Microsoft IMA ADPCM

2022-03-20T16:01:07Z

Cecodere: Created page with "Maybe I am wrong, but according to the Microsoft WAVE AVI Codec registry on the IETF, the codec ID here should be 0x0002 and not 0x0011, where 0x0011 seems to point to Intel's DVI ADPCM instead. Please check [https://www.iana.org/assignments/wave-avi-codec-registry/wave-avi-codec-registry.xml] for more information."

Maybe I am wrong, but according to the Microsoft WAVE AVI Codec registry on the IETF, the codec ID here should be 0x0002 and not 0x0011, where 0x0011 seems to point to Intel's DVI ADPCM instead. Please check [https://www.iana.org/assignments/wave-avi-codec-registry/wave-avi-codec-registry.xml] for more information.

YCbCr

2021-12-17T18:08:06Z

Cecodere:

Many modern video codecs rely on a YCbCr colorspace. The correct written expression for this colorspace is YCbCr, with the 'b' and 'r' characters as subscripts. This is what the components represent:

* Y = luminance, or intensity
* Cb = "blue chrominance", or more precisely the color deviation from gray on a blue-yellow axis
* Cr = "red chrominance", or more precisely the color deviation from gray on a red-cyan axis

Green can be calculated based on these three values.

YCbCr is often falsely mixed up with YUV, which is a different colorspace that is not used in digital media but in analog PAL-based stuff as analog TV transmission or analog video tapes.

Note that with most digital [[RGB]] color encodings, every single pixel has a different R, G and B sample. The same is not true with many YCbCr and also not necessarily true for [[YCoCg|YCoCg]] color encodings. These YCbCr variants operate on the empirical evidence that the human eye is more sensitive to variations in the intensity of a pixel rather than variations in color. Thus, every pixel in an image of such a YCbCr variant has an associated Y sample, but groups of pixels share Cb and Cr samples.

There are different matrix coefficients defined to convert encodings in the RGB color space to YCbCr. Among the more important ones are:

* ITU BT.601 Used for Standard Definition television signals
* ITU T.871 JPEG File Interchange Format (JFIF)
* ITU BT.709 Used for High definition television (HDTV)
* ITU BT.2020 Used for Ultra high definition television

Others are proprietary or less widely used, such as those defined in [[Cinepak]] and SMPTE 240M.

For information on specific YCbCr formats, see the [[:Category:YCbCr Formats|YCbCr formats category page]].

[[Category:Compression Theory]]

YCbCr

2021-12-17T18:07:30Z

Cecodere:

Many modern video codecs rely on a YCbCr colorspace. The correct written expression for this colorspace is YCbCr, with the 'b' and 'r' characters as subscripts. This is what the components represent:

* Y = luminance, or intensity
* Cb = "blue chrominance", or more precisely the color deviation from gray on a blue-yellow axis
* Cr = "red chrominance", or more precisely the color deviation from gray on a red-cyan axis

Green can be calculated based on these three values.

YCbCr is often falsely mixed up with YUV, which is a different colorspace that is not used in digital media but in analog PAL-based stuff as analog TV transmission or analog video tapes.

Note that with most digital [[RGB]] color encodings, every single pixel has a different R, G and B sample. The same is not true with many YCbCr and also not necessarily true for [[YCoCg|YCoCg]] color encodings. These YCbCr variants operate on the empirical evidence that the human eye is more sensitive to variations in the intensity of a pixel rather than variations in color. Thus, every pixel in an image of such a YCbCr variant has an associated Y sample, but groups of pixels share Cb and Cr samples.

There are different matrix coefficients defined to convert encodings in the RGB color space to YCbCr. Among the more important ones are:

* ITU BT.601 Mainly used for Standard Definition television signals
* ITU T.871 JPEG File Interchange Format (JFIF)
* ITU BT.709 Mainly used for High definition television (HDTV)
* ITU BT.2020 Mainly used for Ultra high definition television

Others are proprietary or less widely used, such as those defined in [[Cinepak]] and SMPTE 240M.

For information on specific YCbCr formats, see the [[:Category:YCbCr Formats|YCbCr formats category page]].

[[Category:Compression Theory]]

YCbCr

2021-12-17T18:06:03Z

Cecodere:

Many modern video codecs rely on a YCbCr colorspace. The correct written expression for this colorspace is YCbCr, with the 'b' and 'r' characters as subscripts. This is what the components represent:

* Y = luminance, or intensity
* Cb = "blue chrominance", or more precisely the color deviation from gray on a blue-yellow axis
* Cr = "red chrominance", or more precisely the color deviation from gray on a red-cyan axis

Green can be calculated based on these three values.

YCbCr is often falsely mixed up with YUV, which is a different colorspace that is not used in digital media but in analog PAL-based stuff as analog TV transmission or analog video tapes.

Note that with most digital [[RGB]] color encodings, every single pixel has a different R, G and B sample. The same is not true with many YCbCr and also not necessarily true for [[YCoCg|YCoCg]] color encodings. These YCbCr variants operate on the empirical evidence that the human eye is more sensitive to variations in the intensity of a pixel rather than variations in color. Thus, every pixel in an image of such a YCbCr variant has an associated Y sample, but groups of pixels share Cb and Cr samples.

There are different matrix coefficients defined to convert RGB color space to YCbCr. Among the more important ones are:

* ITU BT.601 Mainly used for Standard Definition television signals
* ITU T.871 JPEG File Interchange Format (JFIF)
* ITU BT.709 Mainly used for High definition television (HDTV)
* ITU BT.2020 Mainly used for Ultra high definition television

Others are proprietary or less widely used, such as those defined in [[Cinepak]] and SMPTE 240M.

For information on specific YCbCr formats, see the [[:Category:YCbCr Formats|YCbCr formats category page]].

[[Category:Compression Theory]]

YCbCr

2021-12-17T18:05:25Z

Cecodere: Provide more information on origins of YCbCr formats

Many modern video codecs rely on a YCbCr colorspace. The correct written expression for this colorspace is YCbCr, with the 'b' and 'r' characters as subscripts. This is what the components represent:

* Y = luminance, or intensity
* Cb = "blue chrominance", or more precisely the color deviation from gray on a blue-yellow axis
* Cr = "red chrominance", or more precisely the color deviation from gray on a red-cyan axis

Green can be calculated based on these three values.

YCbCr is often falsely mixed up with YUV, which is a different colorspace that is not used in digital media but in analog PAL-based stuff as analog TV transmission or analog video tapes.

Note that with most digital [[RGB]] color encodings, every single pixel has a different R, G and B sample. The same is not true with many YCbCr and also not necessarily true for [[YCoCg|YCoCg]] color encodings. These YCbCr variants operate on the empirical evidence that the human eye is more sensitive to variations in the intensity of a pixel rather than variations in color. Thus, every pixel in an image of such a YCbCr variant has an associated Y sample, but groups of pixels share Cb and Cr samples.

There are different matrix coefficients defined to convert RGB color space to YCbCr. Among the more important ones are:

* ITU BT.601 Mainly used for Standard Definition television signals
* ITU T-871 JPEG File Interchange Format (JFIF)
* ITU BT.709 Mainly used for High definition television (HDTV)
* ITU BT.2020 Mainly used for Ultra high definition television

Others are proprietary or less widely used, such as those defined in [[Cinepak]] and SMPTE 240M.

For information on specific YCbCr formats, see the [[:Category:YCbCr Formats|YCbCr formats category page]].

[[Category:Compression Theory]]

YUV4MPEG2

2021-12-17T17:51:59Z

Cecodere:

* Extension: .y4m
* Samples: http://samples.mplayerhq.hu/yuv4mpeg2/

YUV4MPEG2 is a simple file format designed to hold uncompressed frames of [[YCbCr]] video formatted as [[YCbCr 4:2:0]], [[YCbCr 4:2:2]] or [[YCbCr 4:4:4]] data for the purpose of encoding, likely to [[MPEG]]-2. The part "YUV" in its name just derives from the fact that the color space YCbCr (used for color encoding in digital media) is often falsely mixed up with the color space YUV (used in analog PAL based applications, including analog TV and video tapes). Since the original MPEG-2 specification supports more than one type of color matrix (BT.601, BT.709, ...), there is no way to know, without extensions in this format, the color matrix used for conversion to YCbCr from RGB.

== Data Format ==
A Y4M file begins with a plaintext, quasi-freeform header. The first 10 bytes are a file signature of 'YUV4MPEG2 ' (last character is a space, ASCII 0x20). Following the signature is any number of parameters preceeded by a space (ASCII 0x20). The parameters that should definitely be present are width, height, and frame rate:
* frame width: 'W' followed by a plaintext integer; example: 'W720'
* frame height: 'H' followed by a plaintext integer; example: 'H480'
* frame rate: 'F' followed by the number of frames per second, expressed as a fraction in the form numerator:denominator. Examples:
** 'F30:1' = 30 FPS
** 'F25:1' = 25 FPS (PAL/SECAM standard)
** 'F24:1' = 24 FPS (Film)
** 'F30000:1001' = 29.97 FPS (NTSC standard)
** 'F24000:1001' = 23.976 FPS (Film transferred to NTSC)
* interlacing: 'I' followed by a single letter to indicate interlacing mode:
** 'Ip' = Progressive
** 'It' = Top field first
** 'Ib' = Bottom field first
** 'Im' = Mixed modes (detailed in FRAME headers)
* Parameter 'A': Pixel aspect ratio. Note that this is not the ratio of the picture as a whole, just the pixels. Examples:
** 'A0:0' = unknown
** 'A1:1' = square pixels
** 'A4:3' = NTSC-SVCD (480x480 stretched to 4:3 screen)
** 'A4:5' = NTSC-DVD narrow-screen (720x480 compressed to a 4:3 display)
** 'A32:27' = NTSC-DVD wide-screen (720x480 stretched to a 16:9 display)
* Parameter 'C': Colour space
** 'C420jpeg' = 4:2:0 with biaxially-displaced chroma planes
** 'C420paldv' = 4:2:0 with vertically-displaced chroma planes
** 'C420' = 4:2:0 with coincident chroma planes
** 'C422' = 4:2:2
** 'C444' = 4:4:4
** 'Cmono' = YCbCr plane only
* Parameter 'X': Comment or extension. Ignored, but passed, by a YUV4MPEG2 processor.
** FFMPEG defines, among others, the following extensions:
*** 'XCOLORRANGE' providing information on the color space
**** 'XCOLORRANGE=FULL' JPEG / Full swing / ITU T.871 range
**** 'XCOLORRANGE=LIMITED' MPEG / Studio swing / TV range

If you have trouble figuring out the difference between C420jpeg and C420paldv, this might help: https://chromium.googlesource.com/webm/libvpx/+/refs/heads/main/y4minput.c

Following the header is any number of frames coded in YCbCr format in Y-Cb-Cr plane order. Each frame begins with the 5 bytes 'FRAME' followed by zero or more parameters each preceded by 0x20, ending with 0x0A. This is then followed by the raw bytes from each plane.

The length of each frame (excluding its header) can be computed as:

* frame length = width * height * 3 / 2 (4:2:0)
* frame length = width * height * 2 (4:2:2)
* frame length = width * height * 3 (4:4:4)

[[Category:Container Formats]]

YUV4MPEG2

2021-12-17T17:51:29Z

Cecodere: Clarify limitation of format in regards to color matrix coefficients

* Extension: .y4m
* Samples: http://samples.mplayerhq.hu/yuv4mpeg2/

YUV4MPEG2 is a simple file format designed to hold uncompressed frames of [[YCbCr]] video formatted as [[YCbCr 4:2:0]], [[YCbCr 4:2:2]] or [[YCbCr 4:4:4]] data for the purpose of encoding, likely to [[MPEG]]-2. The part "YUV" in its name just derives from the fact that the color space YCbCr (used for color encoding in digital media) is often falsely mixed up with the color space YUV (used in analog PAL based applications, including analog TV and video tapes). Since the original MPEG-2 specification supports more than one type of color matrix (BT.601, BT.709), there is no way to know, without extensions, the color matrix used for conversion to YCbCr from RGB.

== Data Format ==
A Y4M file begins with a plaintext, quasi-freeform header. The first 10 bytes are a file signature of 'YUV4MPEG2 ' (last character is a space, ASCII 0x20). Following the signature is any number of parameters preceeded by a space (ASCII 0x20). The parameters that should definitely be present are width, height, and frame rate:
* frame width: 'W' followed by a plaintext integer; example: 'W720'
* frame height: 'H' followed by a plaintext integer; example: 'H480'
* frame rate: 'F' followed by the number of frames per second, expressed as a fraction in the form numerator:denominator. Examples:
** 'F30:1' = 30 FPS
** 'F25:1' = 25 FPS (PAL/SECAM standard)
** 'F24:1' = 24 FPS (Film)
** 'F30000:1001' = 29.97 FPS (NTSC standard)
** 'F24000:1001' = 23.976 FPS (Film transferred to NTSC)
* interlacing: 'I' followed by a single letter to indicate interlacing mode:
** 'Ip' = Progressive
** 'It' = Top field first
** 'Ib' = Bottom field first
** 'Im' = Mixed modes (detailed in FRAME headers)
* Parameter 'A': Pixel aspect ratio. Note that this is not the ratio of the picture as a whole, just the pixels. Examples:
** 'A0:0' = unknown
** 'A1:1' = square pixels
** 'A4:3' = NTSC-SVCD (480x480 stretched to 4:3 screen)
** 'A4:5' = NTSC-DVD narrow-screen (720x480 compressed to a 4:3 display)
** 'A32:27' = NTSC-DVD wide-screen (720x480 stretched to a 16:9 display)
* Parameter 'C': Colour space
** 'C420jpeg' = 4:2:0 with biaxially-displaced chroma planes
** 'C420paldv' = 4:2:0 with vertically-displaced chroma planes
** 'C420' = 4:2:0 with coincident chroma planes
** 'C422' = 4:2:2
** 'C444' = 4:4:4
** 'Cmono' = YCbCr plane only
* Parameter 'X': Comment or extension. Ignored, but passed, by a YUV4MPEG2 processor.
** FFMPEG defines, among others, the following extensions:
*** 'XCOLORRANGE' providing information on the color space
**** 'XCOLORRANGE=FULL' JPEG / Full swing / ITU T.871 range
**** 'XCOLORRANGE=LIMITED' MPEG / Studio swing / TV range

If you have trouble figuring out the difference between C420jpeg and C420paldv, this might help: https://chromium.googlesource.com/webm/libvpx/+/refs/heads/main/y4minput.c

Following the header is any number of frames coded in YCbCr format in Y-Cb-Cr plane order. Each frame begins with the 5 bytes 'FRAME' followed by zero or more parameters each preceded by 0x20, ending with 0x0A. This is then followed by the raw bytes from each plane.

The length of each frame (excluding its header) can be computed as:

* frame length = width * height * 3 / 2 (4:2:0)
* frame length = width * height * 2 (4:2:2)
* frame length = width * height * 3 (4:4:4)

[[Category:Container Formats]]

YUV4MPEG2

2021-12-17T17:33:46Z

Cecodere:

* Extension: .y4m
* Samples: http://samples.mplayerhq.hu/yuv4mpeg2/

YUV4MPEG2 is a simple file format designed to hold uncompressed frames of [[YCbCr]] video formatted as [[YCbCr 4:2:0]], [[YCbCr 4:2:2]] or [[YCbCr 4:4:4]] data for the purpose of encoding, likely to [[MPEG]]-2. The part "YUV" in its name just derives from the fact that the color space YCbCr (used for color encoding in digital media) is often falsely mixed up with the color space YUV (used in analog PAL based applications, including analog TV and video tapes).

== Data Format ==
A Y4M file begins with a plaintext, quasi-freeform header. The first 10 bytes are a file signature of 'YUV4MPEG2 ' (last character is a space, ASCII 0x20). Following the signature is any number of parameters preceeded by a space (ASCII 0x20). The parameters that should definitely be present are width, height, and frame rate:
* frame width: 'W' followed by a plaintext integer; example: 'W720'
* frame height: 'H' followed by a plaintext integer; example: 'H480'
* frame rate: 'F' followed by the number of frames per second, expressed as a fraction in the form numerator:denominator. Examples:
** 'F30:1' = 30 FPS
** 'F25:1' = 25 FPS (PAL/SECAM standard)
** 'F24:1' = 24 FPS (Film)
** 'F30000:1001' = 29.97 FPS (NTSC standard)
** 'F24000:1001' = 23.976 FPS (Film transferred to NTSC)
* interlacing: 'I' followed by a single letter to indicate interlacing mode:
** 'Ip' = Progressive
** 'It' = Top field first
** 'Ib' = Bottom field first
** 'Im' = Mixed modes (detailed in FRAME headers)
* Parameter 'A': Pixel aspect ratio. Note that this is not the ratio of the picture as a whole, just the pixels. Examples:
** 'A0:0' = unknown
** 'A1:1' = square pixels
** 'A4:3' = NTSC-SVCD (480x480 stretched to 4:3 screen)
** 'A4:5' = NTSC-DVD narrow-screen (720x480 compressed to a 4:3 display)
** 'A32:27' = NTSC-DVD wide-screen (720x480 stretched to a 16:9 display)
* Parameter 'C': Colour space
** 'C420jpeg' = 4:2:0 with biaxially-displaced chroma planes
** 'C420paldv' = 4:2:0 with vertically-displaced chroma planes
** 'C420' = 4:2:0 with coincident chroma planes
** 'C422' = 4:2:2
** 'C444' = 4:4:4
** 'Cmono' = YCbCr plane only
* Parameter 'X': Comment or extension. Ignored, but passed, by a YUV4MPEG2 processor.
** FFMPEG defines, among others, the following extensions:
*** 'XCOLORRANGE' providing information on the color space
**** 'XCOLORRANGE=FULL' JPEG / Full swing / ITU T.871 range
**** 'XCOLORRANGE=LIMITED' MPEG / Studio swing / TV range

If you have trouble figuring out the difference between C420jpeg and C420paldv, this might help: https://chromium.googlesource.com/webm/libvpx/+/refs/heads/main/y4minput.c

Following the header is any number of frames coded in YCbCr format in Y-Cb-Cr plane order. Each frame begins with the 5 bytes 'FRAME' followed by zero or more parameters each preceded by 0x20, ending with 0x0A. This is then followed by the raw bytes from each plane.

The length of each frame (excluding its header) can be computed as:

* frame length = width * height * 3 / 2 (4:2:0)
* frame length = width * height * 2 (4:2:2)
* frame length = width * height * 3 (4:4:4)

[[Category:Container Formats]]

YUV4MPEG2

2021-12-17T17:26:07Z

Cecodere: Small typo on extension name

* Extension: .y4m
* Samples: http://samples.mplayerhq.hu/yuv4mpeg2/

YUV4MPEG2 is a simple file format designed to hold uncompressed frames of [[YCbCr]] video formatted as [[YCbCr 4:2:0]], [[YCbCr 4:2:2]] or [[YCbCr 4:4:4]] data for the purpose of encoding, likely to [[MPEG]]-2. The part "YUV" in its name just derives from the fact that the color space YCbCr (used for color encoding in digital media) is often falsely mixed up with the color space YUV (used in analog PAL based applications, including analog TV and video tapes).

== Data Format ==
A Y4M file begins with a plaintext, quasi-freeform header. The first 10 bytes are a file signature of 'YUV4MPEG2 ' (last character is a space, ASCII 0x20). Following the signature is any number of parameters preceeded by a space (ASCII 0x20). The parameters that should definitely be present are width, height, and frame rate:
* frame width: 'W' followed by a plaintext integer; example: 'W720'
* frame height: 'H' followed by a plaintext integer; example: 'H480'
* frame rate: 'F' followed by the number of frames per second, expressed as a fraction in the form numerator:denominator. Examples:
** 'F30:1' = 30 FPS
** 'F25:1' = 25 FPS (PAL/SECAM standard)
** 'F24:1' = 24 FPS (Film)
** 'F30000:1001' = 29.97 FPS (NTSC standard)
** 'F24000:1001' = 23.976 FPS (Film transferred to NTSC)
* interlacing: 'I' followed by a single letter to indicate interlacing mode:
** 'Ip' = Progressive
** 'It' = Top field first
** 'Ib' = Bottom field first
** 'Im' = Mixed modes (detailed in FRAME headers)
* Parameter 'A': Pixel aspect ratio. Note that this is not the ratio of the picture as a whole, just the pixels. Examples:
** 'A0:0' = unknown
** 'A1:1' = square pixels
** 'A4:3' = NTSC-SVCD (480x480 stretched to 4:3 screen)
** 'A4:5' = NTSC-DVD narrow-screen (720x480 compressed to a 4:3 display)
** 'A32:27' = NTSC-DVD wide-screen (720x480 stretched to a 16:9 display)
* Parameter 'C': Colour space
** 'C420jpeg' = 4:2:0 with biaxially-displaced chroma planes
** 'C420paldv' = 4:2:0 with vertically-displaced chroma planes
** 'C420' = 4:2:0 with coincident chroma planes
** 'C422' = 4:2:2
** 'C444' = 4:4:4
** 'Cmono' = YCbCr plane only
* Parameter 'X': Comment or extension. Ignored, but passed, by a YUV4MPEG2 processor.
** FFMPEG defines, among others, the following extensions:
*** 'XCOLORRANGE' providing information on the color space
**** 'XCOLORRANGE=FULL' JPEG / Full swing / ITU T.871 range
**** 'XCOLORRANGE=LIMITED' BT.601 MPEG range

If you have trouble figuring out the difference between C420jpeg and C420paldv, this might help: https://chromium.googlesource.com/webm/libvpx/+/refs/heads/main/y4minput.c

Following the header is any number of frames coded in YCbCr format in Y-Cb-Cr plane order. Each frame begins with the 5 bytes 'FRAME' followed by zero or more parameters each preceded by 0x20, ending with 0x0A. This is then followed by the raw bytes from each plane.

The length of each frame (excluding its header) can be computed as:

* frame length = width * height * 3 / 2 (4:2:0)
* frame length = width * height * 2 (4:2:2)
* frame length = width * height * 3 (4:4:4)

[[Category:Container Formats]]

YUV4MPEG2

2021-12-17T17:24:21Z

Cecodere: Additional description of parameters taken from FFMPEG

* Extension: .y4m
* Samples: http://samples.mplayerhq.hu/yuv4mpeg2/

YUV4MPEG2 is a simple file format designed to hold uncompressed frames of [[YCbCr]] video formatted as [[YCbCr 4:2:0]], [[YCbCr 4:2:2]] or [[YCbCr 4:4:4]] data for the purpose of encoding, likely to [[MPEG]]-2. The part "YUV" in its name just derives from the fact that the color space YCbCr (used for color encoding in digital media) is often falsely mixed up with the color space YUV (used in analog PAL based applications, including analog TV and video tapes).

== Data Format ==
A Y4M file begins with a plaintext, quasi-freeform header. The first 10 bytes are a file signature of 'YUV4MPEG2 ' (last character is a space, ASCII 0x20). Following the signature is any number of parameters preceeded by a space (ASCII 0x20). The parameters that should definitely be present are width, height, and frame rate:
* frame width: 'W' followed by a plaintext integer; example: 'W720'
* frame height: 'H' followed by a plaintext integer; example: 'H480'
* frame rate: 'F' followed by the number of frames per second, expressed as a fraction in the form numerator:denominator. Examples:
** 'F30:1' = 30 FPS
** 'F25:1' = 25 FPS (PAL/SECAM standard)
** 'F24:1' = 24 FPS (Film)
** 'F30000:1001' = 29.97 FPS (NTSC standard)
** 'F24000:1001' = 23.976 FPS (Film transferred to NTSC)
* interlacing: 'I' followed by a single letter to indicate interlacing mode:
** 'Ip' = Progressive
** 'It' = Top field first
** 'Ib' = Bottom field first
** 'Im' = Mixed modes (detailed in FRAME headers)
* Parameter 'A': Pixel aspect ratio. Note that this is not the ratio of the picture as a whole, just the pixels. Examples:
** 'A0:0' = unknown
** 'A1:1' = square pixels
** 'A4:3' = NTSC-SVCD (480x480 stretched to 4:3 screen)
** 'A4:5' = NTSC-DVD narrow-screen (720x480 compressed to a 4:3 display)
** 'A32:27' = NTSC-DVD wide-screen (720x480 stretched to a 16:9 display)
* Parameter 'C': Colour space
** 'C420jpeg' = 4:2:0 with biaxially-displaced chroma planes
** 'C420paldv' = 4:2:0 with vertically-displaced chroma planes
** 'C420' = 4:2:0 with coincident chroma planes
** 'C422' = 4:2:2
** 'C444' = 4:4:4
** 'Cmono' = YCbCr plane only
* Parameter 'X': Comment or extension. Ignored, but passed, by a YUV4MPEG2 processor.
** FFMPEG defines, among others, the following extensions:
*** 'XCOLORSPACE' providing information on the color space
**** 'XCOLORSPACE=FULL' JPEG / Full swing / ITU T.871 range
**** 'XCOLORSPACE=LIMITED' BT.601 MPEG range

If you have trouble figuring out the difference between C420jpeg and C420paldv, this might help: https://chromium.googlesource.com/webm/libvpx/+/refs/heads/main/y4minput.c

Following the header is any number of frames coded in YCbCr format in Y-Cb-Cr plane order. Each frame begins with the 5 bytes 'FRAME' followed by zero or more parameters each preceded by 0x20, ending with 0x0A. This is then followed by the raw bytes from each plane.

The length of each frame (excluding its header) can be computed as:

* frame length = width * height * 3 / 2 (4:2:0)
* frame length = width * height * 2 (4:2:2)
* frame length = width * height * 3 (4:4:4)

[[Category:Container Formats]]

Cinepak

2021-09-09T05:21:50Z

Cecodere: Clarify the colorspace matrix usage

* FourCC: CVID
* Company: [[Supermac]], [[Radius]], [[Providenza & Boekelheide, Inc.]]
* Technical Description: http://www.csse.monash.edu.au/%7etimf/videocodec/cinepak.txt ([[Mirrored Files|mirrored]])
* Samples: [http://samples.mplayerhq.hu/V-codecs/CVID/ http://samples.mplayerhq.hu/V-codecs/CVID/]
* Windows binary codec: [http://www.probo.com/cinepak.htm http://www.probo.com/cinepak.htm]

The Cinepak coding method is a vector quantization scheme with interframe update optimization. It is known to operate most commonly using a modified YUV 4:2:0 colorspace but also supports 256-grayscale and palettized mode. A modified variant of this format is used for full motion video on many Sega Saturn games (in [[Sega FILM]] files often bearing the .cpk extension). It is not known if this format has anything in common with the [[Cinepak For Sega]] format used in many Sega CD games.

According to https://en.wikipedia.org/wiki/Cinepak (as of 2013-07-27) Cinepak was released in 1991. There is also a patent which seems to approximately describe the codec: http://www.patentstorm.us/patents/5467413/fulltext.html
"Patent 5467413 Issued on November 14, 1995. Estimated Expiration Date: May 20, 2013", submitted 05/20/1993.

The old technology is still being used. As of 2012: "Cinepak Codec for 64 bit is now available" http://beyonddesign.typepad.com/posts/2012/09/service-pack-2-now-available-for-autodesk-navisworks-2013.html

The codec has a very low decoding complexity. With Motorola 68k CPUs at 25 to 33MHz it is known to be well playable as 320x240 2175kbits/sec at 15fps. For a better visual quality with those CPUs 24fps, 320x240, 1800kbps could be recommended (according to http://www.synack.net/~bbraun/68kvideo.html written Jan. 23 2010).

There are several versions of a binary proprietary encoder/decoder as a windows dll, among others ftp://ftp.probo.com/pub/cinepak/cvid32.zip, these dlls can be used on other platforms via "mencoder -ovc vfw -xvfwopts codec=iccvid.dll".

ffmpeg includes both a decoder and an encoder for Cinepak (the encoder draft was written by Tomas Härdin in 2011, made operational and submitted to ffmpeg in January 2014 by Rl @ Aetey). The encoder is simple and quite straightforward, not optimized for speed. It is much slower than its proprietary counterpart but has better quality/bitrate (a double blind test would be welcome).

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Technical notes:

x1, x2 and y1, y2 strip coordinates are absolute, unless y1==0 and the strip is not the first one on the frame - then y1 is assumed to coincide with y2 from the previous strip and the read y2 contains the strip height, i.e. ''if(read_y1==0){ y1 = previous_y2; y2 = previous_y2 + read_y2; }''

Vintage players on both Windows and MacOS work only if the number of strips per frame does not exceed 3.

MacOS player needs codebook definitions always to be present even for empty codebooks, in strict order (v4, then v1).

The technical description does not indicate it, but the conversion matrix from conversion to YUV and RGB color space seems to be as follows:
<pre>
| y | | 0 | | 0.2857 0.5714 0.1429 | | r |
| u | = |128| + | -0.1429 -0.2857 0.4286 | | g |
| v | |128| | 0.3571 -0.2857 -0.0714 | | b |
</pre>

The same is true for the inverse matrix:

<pre>
| r | | 1.0 0.0 2.0 | | y |
| g | = | 1.0 -0.5 -1.0 | | u - 128 |
| b | | 1.0 2.0 0.0 | | v - 128 |
</pre>

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[[Category:Video Codecs]]