VPAAMP-857:False underflow fired after seek+fragment-retry - #1783
Open
varshnie wants to merge 2 commits into
Open
VPAAMP-857:False underflow fired after seek+fragment-retry#1783varshnie wants to merge 2 commits into
varshnie wants to merge 2 commits into
Conversation
Reason for change:GStreamer reports a stale pre-seek position during seek+fragment-retry,causing NotifyVideoFragment to compute negative bufferSec which triggered an immediate false underflow. Fixed by disarming on negative bufferSec and passing 0.0f rate when pipeline is intentionally paused. Risks: p1 Signed-off-by: varshnie <varshniblue14@gmail.com>
Contributor
There was a problem hiding this comment.
Pull request overview
Fixes a false video underflow being raised after seek + fragment-retry by making the underflow monitor treat “impossible” negative buffer depth as a stale GStreamer position and by explicitly disarming deadlines when the pipeline is intentionally paused.
Changes:
- Pass
playRate=0.0fto the underflow monitor when the sink is intentionally paused, so the monitor disarms instead of arming. - In
AampUnderflowMonitor::NotifyVideoFragment, disarm (instead of clamping) when computedbufferSecis negative to avoid immediate false underflow. - On user pause (
SetRateInternal(rate==0)), notify the underflow monitor that the pipeline is paused so deadlines are disarmed.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
| MediaStreamContext.cpp | Adjusts NotifyVideoFragmentToUnderflowMonitor() call sites to pass 0-rate while paused. |
| main_aamp.cpp | Disarms underflow monitoring when the user pauses the pipeline. |
| AampUnderflowMonitor.cpp | Treats negative bufferSec as stale position and disarms the deadline. |
Comments suppressed due to low confidence (1)
MediaStreamContext.cpp:760
- Same issue as the earlier LL-DASH chunk path:
mSinkPausedis true during buffering underflow as well as user pause, andNotifyVideoFragment()needs a non-zeroplayRateduring underflow recovery so it can rearm the deadline after it resumes the pipeline.
// aamp->rate is the last non-zero rate and stays 1.0 even when paused.
// Pass 0.0f when mSinkPaused so RearmDeadline disarms instead of arming.
context->NotifyVideoFragmentToUnderflowMonitor(
dlInfo->absolutePosition + dlInfo->fragmentDurationSec,
aamp->mSinkPaused.load() ? 0.0f : aamp->rate);
Vinish100
reviewed
Jul 28, 2026
| // download retry is in progress and GStreamer hasn't flushed yet). Disarm | ||
| // the deadline rather than clamping to 0, which would trigger an immediate | ||
| // false underflow. | ||
| if (bufferSec < 0.0) |
Contributor
There was a problem hiding this comment.
Lets wait for @pstroffolino review comment.
Current behavior -> if bogus position received from GStreamer, bufferSec drops negative and underflow is fired
Impact -> While receiving bogus position, underflow monitor is disarmed, thus not impacting playback as well as losing underflow detection
varshnie
force-pushed
the
feature/VPAAMP-857
branch
2 times, most recently
from
August 3, 2026 09:46
245aa61 to
ad24ebe
Compare
Reason for change:GStreamer reports a stale pre-seek position during seek+fragment-retry,causing NotifyVideoFragment to compute negative bufferSec which triggered an immediate false underflow. Fixed by disarming on negative bufferSec and passing 0.0f rate when pipeline is intentionally paused. Risks: p1 Signed-off-by: varshnie <varshniblue14@gmail.com>
varshnie
force-pushed
the
feature/VPAAMP-857
branch
from
August 3, 2026 09:48
ad24ebe to
c2d818f
Compare
Vinish100
reviewed
Aug 4, 2026
| // false underflow. | ||
| if (bufferSec < 0.0) | ||
| { | ||
| AAMPLOG_WARN("[video] negative bufferSec=%.3f (endPos=%.3f positionSec=%.3f) — stale GSTpos; disarming deadline", |
| // paused by the user. This disarms the deadline so that fragments | ||
| // downloaded while paused (e.g. during seek-while-paused) do not | ||
| // trigger a false underflow via NotifyVideoFragment. | ||
| if (aamp->mpStreamAbstractionAAMP) |
Contributor
There was a problem hiding this comment.
Check for retVal before calling NotifyPipelinePausedToUnderflowMonitor, will help plug any issues if pipeline didn't pause
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
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.
Reason for change:GStreamer reports a stale pre-seek position during seek+fragment-retry,causing NotifyVideoFragment to compute negative bufferSec which triggered an immediate false underflow. Fixed by disarming on negative bufferSec and passing 0.0f rate when pipeline is intentionally paused. Risks: p1