HLS CEA608 closed caption drops characters issue

[linhai326]

Issue description

The test HLS content has cea608 track and WebVtt track. Using demo player to stream this content, the WebVTT shows correctly while the cea608 track keeps dropping lines.

Reproduction steps

start the test content link below, the issue can start to happen at 00:01:02 position. the cea608 will drop lines while webvtt can show correctly.

comparing with other players, like http://hlstester.com/, https://developer.jwplayer.com/tools/stream-tester/
these players don't drop lines from cea608 track.

Link to test content

http://vod-staging-msp-ops.mobitv.com/mm/hls5/vod/291/984111/VODSERVICE_1354/group=TG_W_4G,drm=native.m3u8?uid=45dd8d07-d953-4a2c-b823-edb138f5e604&sid=73119663582491516668432&i=0&nwk=&pk=1

Version of ExoPlayer being used

this happens on all versions from 2.1.x to 2.6.1.

Device(s) and version(s) of Android being used

on all devices: firetv stick gen2, LG-TP450, Samsung Note3...

A full bug report captured from the device

a full adb log attached.
also i put log printout in cea608decoder.java in private void handleMiscCode(byte cc2) :
"
...
if (captionMode == CC_MODE_UNKNOWN) {
return;
}
System.out.println("TESTTEST cc2 event = " + Integer.toHexString(cc2));
switch (cc2) {
case CTRL_ERASE_DISPLAYED_MEMORY:
cues = null;
if (captionMode == CC_MODE_ROLL_UP || captionMode == CC_MODE_PAINT_ON) {
resetCueBuilders();
}
break;
case CTRL_ERASE_NON_DISPLAYED_MEMORY:
...
"
this gives out the cause of the lines dropped:
"
...
02-01 10:24:28.265 17371-17647/com.google.android.exoplayer2.demo I/System.out: TESTTEST append2: c
02-01 10:24:28.265 17371-17647/com.google.android.exoplayer2.demo I/System.out: TESTTEST append: a
02-01 10:24:28.265 17371-17647/com.google.android.exoplayer2.demo I/System.out: TESTTEST append2: t
02-01 10:24:28.265 17371-17647/com.google.android.exoplayer2.demo I/System.out: TESTTEST append: s
02-01 10:24:28.265 17371-17647/com.google.android.exoplayer2.demo I/System.out: TESTTEST append2: .
02-01 10:24:28.266 17371-17647/com.google.android.exoplayer2.demo I/System.out: TESTTEST cc2 event = 2c
02-01 10:24:31.288 17371-17647/com.google.android.exoplayer2.demo I/System.out: TESTTEST cc2 event = 2e
02-01 10:24:31.288 17371-17647/com.google.android.exoplayer2.demo I/System.out: TESTTEST append: H
02-01 10:24:31.288 17371-17647/com.google.android.exoplayer2.demo I/System.out: TESTTEST append2: e
02-01 10:24:31.288 17371-17647/com.google.android.exoplayer2.demo I/System.out: TESTTEST append: y
...
"
the CTRL_ERASE_NON_DISPLAYED_MEMORY command removed all characters before it and didn't display it.
why does the decoder do that?

[linhai326]

cea608_decoder_log.txt
fulllog.txt

[linhai326]

Hi @AquilesCanta , any update/findings on this issue?

[ojw28]

This is an issue where we're not correctly keeping buffers with identical presentation timestamps in their original order. We will push a fix shortly.

[linhai326]

that's a great news, Thanks!