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MVDSTD:CalculateWorkBufSize: Difference between revisions

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Added command detail.
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!  Description
!  Description
|-
|-
| 0
| 00
| Header code [0x00030300]
| Header code [0x00030300]
|-
|-
| 1..12
| 01-03
| ?
| CalculateWorkBufSizeConfig
|-
| 04-10
| ???????????????
|-
| 11
| u32 Video width
|-
| 12
| u32 Video height
|}
|}


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=Description=
=Description=
This calculates the buffer size for [[MVDSTD:Initialize]] using the input parameters. This doesn't write to MVD state / registers at all.
==CalculateWorkBufSizeConfig==
{| class="wikitable" border="1"
|-
!  Offset
!  Description
|-
| 0x00
| Unused
|-
| 0x01-0x04
| CalculateWorkBufWithLevel
|-
| 0x05-0x06
| CalculateWorkBufWithNumOfRefFramesA
|-
| 0x07-0x08
| CalculateWorkBufWithNumOfRefFramesB
|-
| 0x09-0x11
| Unused
|}
 
===CalculateWorkBufWithLevel===
{| class="wikitable" border="1"
|-
!  Offset
!  Description
|-
| 0x00
| bool Enable calculation
|-
| 0x01
| u8 Flag
|-
| 0x02
| bool Double size
|-
| 0x03
| u8 H.264 level
|}
 
====Flag====
{| class="wikitable" border="1"
|-
!  Bit
!  Description
|-
| 0x00
| FLAG_NONE
|-
| 0x01
| FLAG_ENABLE_CALCULATION
|-
| 0x02
| FLAG_ENABLE_EXTRA_OP (see below)
|-
| 0x03
| FLAG_UNK
|}
 
====H.264 level====
{| class="wikitable" border="1"
|-
!  Index
!  Description
|-
| 0x00
| Level 1.0
|-
| 0x01
| Level 1.0b
|-
| 0x02
| Level 1.1
|-
| 0x03
| Level 1.2
|-
| 0x04
| Level 1.3
|-
| 0x05
| Level 2.0
|-
| 0x06
| Level 2.1
|-
| 0x07
| Level 2.2
|-
| 0x08
| Level 3.0
|-
| 0x09
| Level 3.1
|-
| 0x0A
| Level 3.2
|-
| 0x0B
| Level 4.0
|-
| 0x0C
| Level 4.1
|-
| 0x0D
| Level 4.2
|-
| 0x0E
| Level 5.0
|-
| 0x0F
| Level 5.1
|-
| 0x10
| Level 5.2
|}
 
This will calculate maximum possible buffer size (==buffer size that '''''may''''' be needed to decode video) based on H.264 level and resolution, so any videos that are compliant with H.264 specs should be decoded with this buffer size.
 
Calculation procedures are :
* Calculate '''max_reference_frames''' based on '''H.264 level''' and '''resolution''', 0x10 is used if '''max_reference_frames''' is greater than 0x10.
* Calculate '''frame_size''' based on '''resolution'''.
* Multiply '''frame_size''' and '''(max_reference_frames + 1)''' to get '''temp_buffer_size'''
* If FLAG_ENABLE_EXTRA_OP is set, '''temp_buffer_size += (temp_buffer_size / 6)'''
* If double size (offset 0x02) is set, '''temp_buffer_size *= 2'''
* Finally, '''temp_buffer_size += 0xFC8'''
 
To perform calculation, enable calculation (ofset 0x00) '''''and''''' flag (offset 0x01) must be non-zero, otherwise 0 is returned.
 
If resolution is too high for given H.264 level, 0 is returned.
 
Attempting to use more than 0x10 for H.264 level (offset 0x03) will likely cause out-of-bound access.
 
===CalculateWorkBufWithNumOfRefFramesA/B===
{| class="wikitable" border="1"
|-
!  Offset
!  Description
|-
| 0x00
| bool Enable calculation
|-
| 0x01
| u8 Number of reference frames
|}
 
This will calculate buffer size based on resolution and number of reference frames.
 
Calculation procedures are :
* Calculate '''frame_size''' based on '''resolution'''.
* Multiply '''frame_size''' and '''number_of_reference_frames''' to get '''temp_buffer_size'''
* Finally, for CalculateWorkBufWithNumOfRefFrames'''A''', '''temp_buffer_size += 0x10800'''
* Finally, for CalculateWorkBufWithNumOfRefFrames'''B''', '''temp_buffer_size += 0x858'''
 
To perform calculation, enable calculation (ofset 0x00) must be non-zero, otherwise 0 is returned.
 
If number of reference frames (offset 0x01) is less than 0x02, 0x02 is used internally, if it's greater than 0x10, 0x10 is used internally.
 
 
It is possible to enable more than 1 calculation methods simultaneously, in that case the biggest buffer size among them is returned.
 
SKATER uses
```
cmd.CalculateWorkBufWithLevel.enable = 0x01;
cmd.CalculateWorkBufWithLevel.flag = 0x07; //(FLAG_ENABLE_CALCULATION | FLAG_ENABLE_EXTRA_OP | FLAG_UNK).
cmd.CalculateWorkBufWithLevel.doubleSize = 0x00;
cmd.CalculateWorkBufWithLevel.level = 0x0A; //Level 3.2.
cmd.CalculateWorkBufWithNumOfRefFramesA.enable = 0x00;
cmd.CalculateWorkBufWithNumOfRefFramesA.numOfReferenceFrames = 0x00;
cmd.CalculateWorkBufWithNumOfRefFramesB.enable = 0x00;
cmd.CalculateWorkBufWithNumOfRefFramesB.numOfReferenceFrames = 0x00;
cmd.width = 854; //Regardless of input video, 854 is always used.
cmd.height = 480; //Regardless of input video, 480 is always used.
```
and result is 9438920Bytes (0x9006C8), aka MVD_DEFAULT_WORKBUF_SIZE.
 
This doesn't write to MVD state / registers at all.
Retrieved from "https://www.3dbrew.org/wiki/MVDSTD:CalculateWorkBufSize"