Skip to content

Fix edge case for parsing video with constant frame size #20

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 5 commits into from
Sep 16, 2025
Merged

Fix edge case for parsing video with constant frame size #20

Show file tree
Hide file tree
Changes from 2 commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
1c79c78
Fix edge case for parsing video with constant frame size
ntjohnson1 Sep 15, 2025
6c42f76
Appease CI
ntjohnson1 Sep 15, 2025
a3e41e6
Fix while loop condition and reverse if branch when only single sampl…
ntjohnson1 Sep 16, 2025
afe3fc4
Add simple test to verify we parse the samples correctly
ntjohnson1 Sep 16, 2025
d787134
Fix clippy warning
ntjohnson1 Sep 16, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions .typos.toml
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -14,3 +14,4 @@ numer = "numer"
trak = "trak"
trun = "trun"
truns = "truns"
typ = "typ"
2 changes: 1 addition & 1 deletion CHANGELOG.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@

## 0.3.0 - 2024-11-13 - Handle time shifts
* Account for video with DTS shift and resulting negative dts values [#16](https://github.com/rerun-io/re_mp4/pull/16) by [@Wumpf](https://github.com/Wumpf)
* Shift DTS & CTS by minimum CTS to mimick `ffprobe`'s behavior [#17](https://github.com/rerun-io/re_mp4/pull/17) by [@Wumpf](https://github.com/Wumpf)
* Shift DTS & CTS by minimum CTS to mimic `ffprobe`'s behavior [#17](https://github.com/rerun-io/re_mp4/pull/17) by [@Wumpf](https://github.com/Wumpf)


## 0.2.1 - 2024-11-12 - Bug fixes
Expand Down
11 changes: 9 additions & 2 deletions src/reader.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -165,7 +165,10 @@ impl Mp4 {
let stsz = &stbl.stsz;
let stts = &stbl.stts;

while sample_n < stsz.sample_sizes.len() {
// Could probably just always use sample count
while (sample_n < stsz.sample_sizes.len() && sample_n == 0)
|| sample_n < stsz.sample_count as usize
{
Copy link
Member

@emilk emilk Sep 16, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This looks a bit weird 👀

Copy link
Member Author

@ntjohnson1 ntjohnson1 Sep 16, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

It should be && stsz. sample_size == 0 oops

Either sample_sizes should exist as a non-empty vector and sample_size is 0 (showing unused) or sample_size is a constant across all samples. I think we can just always use sample_count but I couldn't find a sufficiently convincing spec to reference (didn't look that hard)

// compute offset
if sample_n == 0 {
chunk_index = 1;
Expand Down Expand Up @@ -208,7 +211,11 @@ impl Mp4 {
}

let timescale = trak.mdia.mdhd.timescale as u64;
let size = stsz.sample_sizes[sample_n] as u64;
let size = if stsz.sample_size != 0 {
stsz.sample_size as u64
} else {
stsz.sample_sizes[sample_n] as u64
};
let offset = get_sample_chunk_offset(stbl, chunk_index) + offset_in_chunk;
offset_in_chunk += size;

Expand Down
Loading