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Fix formatting for corruption detection header explainer.

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Bug: webrtc:358039777
Change-Id: Ic9e860fbfdaf0bfe4b3e1d29f75913fb8d1080d0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/360742
Commit-Queue: Erik Språng <sprang@webrtc.org>
Reviewed-by: Fanny Linderborg <linderborg@webrtc.org>
Auto-Submit: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#42869}
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Erik Språng 2024-08-27 13:29:07 +02:00 committed by WebRTC LUCI CQ
parent b60f0ffbce
commit 54559d354e
1 changed files with 20 additions and 17 deletions
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37
docs/native-code/rtp-hdrext/corruption-detection/README.md
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@ -1,11 +1,14 @@
# Corruption Detection # Corruption Detection
** Name: ** **Name:**
"Corruption Detection"; "Extension for Automatic Detection of Video Corruptions" "Corruption Detection"; "Extension for Automatic Detection of Video Corruptions"
** Formal name: **
**Formal name:**
<http://www.webrtc.org/experiments/rtp-hdrext/corruption-detection> <http://www.webrtc.org/experiments/rtp-hdrext/corruption-detection>
** Status: ** This extension is defined here to allow for experimentation.
** Contact: ** <sprang@google.com> **Status:** This extension is defined here to allow for experimentation.
**Contact:** <sprang@google.com>
NOTE: This explainer is a work in progress and may change without notice. NOTE: This explainer is a work in progress and may change without notice.
@ -14,7 +17,7 @@ detection or ACD) extension is intended to be a part of a system that allows
estimating a likelihood that a video transmission is in a valid state. That is, estimating a likelihood that a video transmission is in a valid state. That is,
the input to the video encoder on the send side corresponds to the output of the the input to the video encoder on the send side corresponds to the output of the
video decoder on the receive side with the only difference being the expected video decoder on the receive side with the only difference being the expected
distortions from lossy compression. distortions from lossy compression.
The goal is to be able to detect outright coding errors caused by things such as The goal is to be able to detect outright coding errors caused by things such as
bugs in encoder/decoders, malformed packetization data, incorrect relay bugs in encoder/decoders, malformed packetization data, incorrect relay
@ -152,7 +155,7 @@ them.
### Sequence Index Handling ### Sequence Index Handling
The quasi-random sequence of choice for this extension is a 2D The quasi-random sequence of choice for this extension is a 2D
[Halton Sequence](https://en.wikipedia.org/wiki/Halton_sequence). [Halton Sequence](https://en.wikipedia.org/wiki/Halton_sequence).
The index into the Halton Sequence is indicated by the header extension and The index into the Halton Sequence is indicated by the header extension and
results in a 14 bit unsigned integer which on overflow will wrap around back to results in a 14 bit unsigned integer which on overflow will wrap around back to
@ -226,11 +229,11 @@ subsampling format. When determining which plane a location belongs to, it is
easiest to visualize it as the chroma planes being “stacked” to the side of the easiest to visualize it as the chroma planes being “stacked” to the side of the
luma plane: luma plane:
+------+---+ +------+---+
| | U | | | U |
+ Y +---+ + Y +---+
| | V | | | V |
+------+---+ +------+---+
In pseudo code: In pseudo code:
``` ```
@ -244,7 +247,7 @@ In pseudo code:
} else { } else {
HandleSample(V_PLANE, row - (image_height / 2), col - image_width); HandleSample(V_PLANE, row - (image_height / 2), col - image_width);
} }
seq_index++; seq_index++;
``` ```
Support for other layout types may be added in later versions of this extension. Support for other layout types may be added in later versions of this extension.
@ -268,14 +271,14 @@ max_d = ceil(sqrt(-2.0 * ln(0.2) * stddev^2) - 1.
Any samples outside the plane are considered to have weight 0. Any samples outside the plane are considered to have weight 0.
In pseudo-code, that means we get the following: In pseudo-code, that means we get the following:
``` ```
sample_sum = 0; sample_sum = 0;
weight_sum = 0; weight_sum = 0;
for (y = max(0, row - max_d) to min(plane_height, row + max_d) { for (y = max(0, row - max_d) to min(plane_height, row + max_d) {
for (x = max(0, col - max_d) to min(plane_width, col + max_d) { for (x = max(0, col - max_d) to min(plane_width, col + max_d) {
weight = e^(-1 * ((y - row)^2 + (x - col)^2) / (2 * stddev^2)); weight = e^(-1 * ((y - row)^2 + (x - col)^2) / (2 * stddev^2));
sample_sum += SampleAt(x, y) * weight; sample_sum += SampleAt(x, y) * weight;
weight_sum += weight; weight_sum += weight;
} }
} }
filtered_sample = sample_sum / weight_sum; filtered_sample = sample_sum / weight_sum;
@ -341,7 +344,7 @@ all.
There are also possibly more accurate but probably much more costly alternatives There are also possibly more accurate but probably much more costly alternatives
as well, such as training an ML model to determine the settings based on both as well, such as training an ML model to determine the settings based on both
the content of the source frame and any metadata present in the encoded the content of the source frame and any metadata present in the encoded
bitstream. bitstream.
Regardless of method, the implementation at the send side SHOULD strive to set Regardless of method, the implementation at the send side SHOULD strive to set
the filter size and error thresholds such that 99.5% of filtered samples end up the filter size and error thresholds such that 99.5% of filtered samples end up