Indeo 5: Difference between revisions

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|-
|-
| 3  || frame_flags || || ||
| 3  || frame_flags || || ||
* frame_flags & 0x01 => backward predictive
* frame_flags
* frame_flags & 0x02 => forward predictive
* frame_flags & 0x04 => null frame
common values:
* 0 => I frame
* 1 => P frame
* 3 => B frame
|-
| 5 || const1 || || || = 0x1F always
|-
| 8 || id_in_gop || || || frame number in GOP (0 for I frame)
|}
 
null frames don't contain anything else than this header.
 
=== GOP header ===
 
This header is present in I frames only. The values in this header are valid during the whole GOP starting at this frame.
 
{| border="1" cellpadding="5" style="border-collapse: collapse; border-style: dashed; border-color: #2f6fab;"
|- bgcolor="#f0f0f0" |
! size !! name !! condition !! nb times !! comments
|-
| align="right" |  8 || <span id="gh_flags">gh_flags</span> || || || [[#gh_flags|gh_flags]] & 0x02 => YV12 (default YVU9)
|-
| align="right" | 16 || <span id="value1">value1</span> || [[#gh_flags|gh_flags]] & 0x01 || ||
|-
| align="right" | 32 || <span id="value2">value2</span> || [[#gh_flags|gh_flags]] & 0x20 || ||
|-
| align="right" |  2 || <span id="value3">value3</span> || [[#gh_flags|gh_flags]] & 0x40 || ||
|-
| align="right" |  3 || <span id="value4">value4</span> || || ||
|-
| align="right" |  4 || <span id="res_id">res_id</span> || || || see [[#Resolution_table|Resolution table]]
|-
| align="right" | 13 || <span id="height">height</span> || rowspan="2" | [[#res_id|res_id]] == 15 || || frame height
|-
| align="right" | 13 || <span id="width">width</span> || || frame width
|-
| align="right" |  6 || <span id="value5">value5</span> || || rowspan="2" | 2*n (n == 1 always?) ||
|-
| align="right" |  2 || <span id="value6">value6</span> || [[#value5|value5]] >> 3 || need to be = 0
|-
| align="right" |  4 || <span id="value7">value7</span> || rowspan="2" | [[#gh_flags|gh_flags]] & 0x08 || ||
|-
| align="right" | 24 || <span id="value8">value8</span> || ||
|-
| align="right" | ?? || <span id="alignment1">alignment1</span> || || || align bits reader on next byte
|-
| align="right" | 24 || <span id="value9">value9</span> || || ||
|-
| align="right" | 16 || <span id="value10">value10</span> || [[#value9|value9]] & 0x800000 || || loops while value10 & 0x8000 (probably some kind of VLC ?)
|}
 
=== More header ===
 
This header is present in all kinds of frame except null.
 
{| border="1" cellpadding="5" style="border-collapse: collapse; border-style: dashed; border-color: #2f6fab;"
|- bgcolor="#f0f0f0" |
! size !! name !! condition !! nb times !! comments
|-
| align="right" |  8 || <span id="mh_flags">mh_flags</span> || || ||
|-
| align="right" | 24 || <span id="frame_size">frame_size</span> || [[#mh_flags|mh_flags]] & 0x01 || || tolal size of frame data
|-
| align="right" | 16 || <span id="value11">value11</span> || [[#mh_flags|mh_flags]] & 0x10 || ||
|-
| align="right" |  8 || <span id="counter1">counter1</span> || rowspan="2" | [[#mh_flags|mh_flags]] & 0x20 || || rowspan="2" | this whole block loops while [[#counter1|counter1]] != 0
|-
| align="right" |  8 || <span id="value12">value12</span> || [[#counter1|counter1]]
|-
| align="right" |  3 || <span id="value13">value13</span> || [[#mh_flags|mh_flags]] & 0x40 || ||
|-
| align="right" |  4 || <span id="counter2">counter2</span> || rowspan="2" | [[#value13|value13]] == 7 || ||
|-
| align="right" |  4 || <span id="value14">value14</span> || [[#counter2|counter2]] ||
|-
| align="right" |  3 || <span id="value15">value15</span> || || ||
|-
| align="right" | ?? || <span id="alignment2">alignment2</span> || || || align bits reader on next byte
|}
 
=== Plan header ===
 
This header is present at the beginning of every plan.
 
{| border="1" cellpadding="5" style="border-collapse: collapse; border-style: dashed; border-color: #2f6fab;"
|- bgcolor="#f0f0f0" |
! size !! name !! condition !! nb times !! comments
|-
| align="right" |  8 || <span id="ph_flags">ph_flags</span> || || ||
|-
| align="right" | 24 || <span id="plan_size">plan_size</span> || [[#mh_flags|mh_flags]] & 0x80 || || tolal size of plan data
|-
| align="right" |  8 || <span id="counter3">counter3</span> || rowspan="3" | [[#ph_flags|ph_flags]] & 0x10 || || must be < 0x3E
|-
| align="right" |  8 || <span id="value16">value16</span> || rowspan="2" | [[#counter3|counter3]] ||
|-
| align="right" |  8 || <span id="value17">value17</span> ||
|-
| align="right" |  3 || <span id="value18">value18</span> || [[#ph_flags|ph_flags]] & 0x40 || ||
|-
| align="right" |  3 || <span id="table1_id">table1_id</span> || [[#ph_flags|ph_flags]] & 0x80 || || see [[#Table_1|Table 1]]
|-
| align="right" |  4 || <span id="counter4">counter4</span> || rowspan="2" | [[#table1_id|table1_id]] == 7 || || rowspan="2" | used instead of [[#Table1|Table1]]
|-
| align="right" |  4 || <span id="value19">value19</span> || [[#counter4|counter4]]
|-
| align="right" |  1 || <span id="value20">value20</span> || || ||
|-
| align="right" | 16 || <span id="value21">value21</span> || [[#value20|value20]] || ||
|-
| align="right" |  5 || <span id="value22">value22</span> || || ||
|-
| align="right" | ?? || <span id="alignment3">alignment3</span> || || || align bits reader on next byte
|-
| align="right" |  8 || <span id="counter5">counter5</span> || rowspan="4" | [[#ph_flags|ph_flags]] & 0x20 || || rowspan="3" | all of this is repeated as long as [[#value23|value23]] is true
|-
| align="right" |  8 || <span id="skip1">skip1</span> || [[#counter5|counter5]]
|-
| align="right" |  1 || <span id="value23">value23</span> ||
|-
| align="right" | ?? || <span id="alignment4">alignment4</span> || || align bits reader on next byte
|}
 
 
== Plan data ==
 
This is where the actual data is, but this still need to be reverse engineered :-(
 
{| border="1" cellpadding="5" style="border-collapse: collapse; border-style: dashed; border-color: #2f6fab;"
|- bgcolor="#f0f0f0" |
! size !! name !! condition !! nb times !! comments
|-
| align="right" |  1 || <span id="value24">value24</span> || || ||
|-
| align="right" |  1 || <span id="value25">value25</span> || ! [[#value24|value24]] || || plan_data_size = value25
|-
| align="right" |  8 || <span id="value26">value26</span> || [[#value25|value25]] == 1 || || plan_data_size = value26
|-
| align="right" | 24 || <span id="value27">value27</span> || [[#value26|value26]] == 0xFF || || plan_data_size = value27
|-
| align="right" | ?? || ... || || || more data to analyze
|}
 
 
== Annexes ==
 
=== Resolution table ===
 
{| border="1" cellpadding="5" style="border-collapse: collapse; border-style: dashed; border-color: #2f6fab;"
! bgcolor="#f0f0f0" | res_id
| 0 || 1 || 2 || 3 || 4 || 5 || 6 || 7 || 8 || 9 || 10 || 11
|-
! bgcolor="#f0f0f0" | width
| 640 || 320 || 160 || 704 || 352 || 352 || 176 || 240 || 640 || 704 || 80 || 88
|-
! bgcolor="#f0f0f0" | height
| 480 || 240 || 120 || 224 || 240 || 288 || 144 || 180 || 240 || 240 || 60 || 72
|}
 
=== Table 1 ===
 
{| border="1" cellpadding="5" style="border-collapse: collapse; border-style: dashed; border-color: #2f6fab;"
! bgcolor="#f0f0f0" | table1_id
| 0 || 1 || 2 || 3 || 4 || 5 || 6 || default
|-
! bgcolor="#f0f0f0" | counter4
| 10 || 11 || 12 || 13 || 11 || 13 || 13 || 9
|-
! valign="top" bgcolor="#f0f0f0" | value19
| valign="top" |
{| border="0"
| 1
|-
| 2
|-
| 3
|-
| 4
|-
| 4
|-
| 7
|-
| 5
|-
| 5
|-
| 4
|-
| 1
|}
| valign="top" |
{| border="0"
| 2
|-
| 3
|-
| 4
|-
| 4
|-
| 4
|-
| 7
|-
| 5
|-
| 4
|-
| 3
|-
| 3
|-
| 2
|}
| valign="top" |
{| border="0"
| 2
|-
| 4
|-
| 5
|-
| 5
|-
| 5
|-
| 5
|-
| 6
|-
| 4
|-
| 4
|-
| 3
|-
| 1
|-
| 1
|}
| valign="top" |
{| border="0"
| 3
|-
| 3
|-
| 4
|-
| 4
|-
| 5
|-
| 6
|-
| 6
|-
| 4
|-
| 4
|-
| 3
|-
| 2
|-
| 1
|-
| 1
|}
| valign="top" |
{| border="0"
| 3
|-
| 4
|-
| 4
|-
| 5
|-
| 5
|-
| 5
|-
| 6
|-
| 5
|-
| 4
|-
| 2
|-
| 2
|}
| valign="top" |
{| border="0"
| 3
|-
| 4
|-
| 5
|-
| 5
|-
| 5
|-
| 5
|-
| 6
|-
| 4
|-
| 3
|-
| 3
|-
| 2
|-
| 1
|-
| 1
|}
| valign="top" |
{| border="0"
| 3
|-
| 4
|-
| 5
|-
| 5
|-
| 5
|-
| 6
|-
| 5
|-
| 4
|-
| 3
|-
| 3
|-
| 2
|-
| 1
|-
| 1
|}
| valign="top" |
{| border="0"
| 3
|-
| 4
|-
| 4
|-
| 5
|-
| 5
|-
| 5
|-
| 6
|-
| 5
|-
| 5
|}
|}
 
default is used when !([[#ph_flags|ph_flags]] & 0x80)
 
 
[[Category:Undiscovered Video Codecs]]
[[Category:Video Codecs]]

Revision as of 16:04, 18 March 2006

General description

Frame layout

The general indeo5 frames layout is composed of one global header, followed by the content of the three YUV plans.

In this document, the global header is split into 3 parts:

  • Frame header: describe the kind of frame (I/P/B)
  • GOP header: some data which is true for all the frame in this GOP (present only in the first (I) frame of the GOP)
  • More header: some more data which is true only for this single frame

Each YUV plan begin with a Plan header, containing values which are valid only for this single plan.

Encoding

This codec is based on the slant transform. Other used standard techniques are huffman coding and motion compensation.

Conventions

Headers are described in some tables. Each row of those tables describes a value which may be read from the frame. Those tables and rows are presented in the order of appearance in the frame.

Here are the meaning of each columns:

  • size: The size of this value in bits. Bits are counted in MSB to LSB order. As an example, with the byte 01110000b, reading 3 bits then 5 bits will return 011b then 10000b.
  • name: Kind of variable name, used to reference the value. When a value is named valueX, it generally means we don't know it's purpose. Lines named alignmentX means that bits reader need to skip bits until next byte boundary.
  • condition: The value is present in the frame only if this condition is matched. No condition means that the value is always present.
  • nb times: How many times the value is repeated.
  • comments: Some details about the content of the value. It may also explain that a value is repeated until a certain condition is reached.


Headers

Frame header

size name condition nb times comments
3 frame_flags
  • frame_flags
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