Fix webm recording when dealing with files that already exist#401
Merged
Fix webm recording when dealing with files that already exist#401
Conversation
1) Append mode overwrites instead of appending: WebmWriter never seeks to
the end of the target file in append mode, so writeTag writes from
offset 0 and destroys existing data
2) Existing file not truncated when rewriting: when append is false, the
final copy writes new data to the destination but never truncates the
file first. If the destination already exists and is larger than the
new content, stale bytes remain at the end, producing a corrupted WebM.
Fixed by:
1) Append mode now seeks to the end of the existing file before writing, so
new data no longer overwrites from offset 0.
2) Rewrite mode truncates the destination before copying temporary data,
preventing stale trailing bytes from older, larger files.
mondain
approved these changes
Nov 26, 2025
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Commit from kdkd fork
792e07fio/webm/WebmWriter.java: Fixed two bugs:
Append mode overwrites instead of appending: WebmWriter never seeks to
the end of the target file in append mode, so writeTag writes from
offset 0 and destroys existing data
Existing file not truncated when rewriting: when append is false, the
final copy writes new data to the destination but never truncates the
file first. If the destination already exists and is larger than the
new content, stale bytes remain at the end, producing a corrupted WebM.
Fixed by:
Append mode now seeks to the end of the existing file before writing, so
new data no longer overwrites from offset 0.
Rewrite mode truncates the destination before copying temporary data,
preventing stale trailing bytes from older, larger files.