TivoHD hardsub'd H.264 playback issue

txporter · 9th February 2010, 19:12

I am trying to find a solution for a playback issue relating to hardsubs in MP4 files encoded with x264. The problem is subtle and I have only seen it when viewing hardsub'ing files on my TivoHD (the videos are fine on the computer). It seems to be a decoding issue and I am hoping to find some settings to eliminate it. The problem that I am seeing is that the subtitles seem to "shimmer" for lack of a better term. But it is not consistent. If I pause the video and frame advance through, I can see places were the subtitles are perfectly displayed, and places were they seem to have tears or something in the text. If I start play again on a location where the subtitles are displayed well, the video will continue to play all of the subtitles well. If I start play again on a location where the subtitles are torn, then all of the subtitles look like this (this is what I am calling shimmering).

It appears that I see less of the tearing subs when I use a ref=1 rather than ref=3. I haven't been able to find any consistent repetition of good/bad sub display when stepping through the video. Usually (not always), the bad subtitles appear 4 frames in a row and then there will be good ones. The # of good sub frames between bad subs is not consistent though.

I have tried baseline, main and high profiles as well as stepping through the presets from ultrafast to placebo. The profiles or the presets do not seem to affect the playback. I have tried the fastdecode and zerolatency tuning profiles, turning dct-decimate off, intra-refresh on, bframes off, trellis off, most all of the parameters on/off.

I am looking for any ideas as to what the problem might be and any possible solutions (or thoughts). One other thing about H.264 playback on the TivoHD (in case it might somehow provide more information for a solution to the subtitle problem): initially, all h.264 encoded video would open with an initial green/blocky screen for the first few seconds. Muxing the audio stream in before the video stream in the mp4 container fixed this issue.

If I use the same avs file and encode the video with HCenc, there are no playback issues. It appears to be a H.264 decode issue on the TivoHD. And just to reiterate, the x264 encoded files play fine on the computer just not the TivoHD.

Source files are NTSC DVDs, ripped to hard drive, merged into 1 mpg with VideoRedo, and indexed with DGIndex with honor pulldown. My avs file is pretty simple.

example.avs

Code:

loadplugin("D:\XviD4PSP5\apps\DGMPGDec\DGDecode.dll")
loadplugin("D:\XviD4PSP5\dlls\AviSynth\plugins\TIVTC.dll")
LoadPlugin("D:\XviD4PSP5\dlls\AviSynth\plugins\FluxSmooth.dll")
LoadPlugin("D:\XviD4PSP5\dlls\AviSynth\plugins\Undot.dll")
loadplugin("D:\XviD4PSP5\dlls\AviSynth\plugins\VSFilter.dll")

MPEG2Source("D:\temp\x264\Rescue.Me.S2E07-clip.d2v",cpu=3)

TFM().TDecimate()
Undot().FluxSmoothT(3)
Lanczos4resize(720,400)

TextSub("D:\temp\x264\Rescue.Me.S2E07-clip.d2v.srt")

x264 command line string that seems to play best (so far):

Code:

x264-r1416.exe --crf 18 --no-psy --keyint 24 --bframes 0 --sar 1:1 --ref 1 -o test.264 example.avs

Could what I use to load the video in avisynth affect this? Or maybe the plugin used to display the subs (is there something beside vsfilter?)?

9th February 2010, 19:12	#1 \| Link
txporter Registered User Join Date: Nov 2009 Posts: 110	TivoHD hardsub'd H.264 playback issue I am trying to find a solution for a playback issue relating to hardsubs in MP4 files encoded with x264. The problem is subtle and I have only seen it when viewing hardsub'ing files on my TivoHD (the videos are fine on the computer). It seems to be a decoding issue and I am hoping to find some settings to eliminate it. The problem that I am seeing is that the subtitles seem to "shimmer" for lack of a better term. But it is not consistent. If I pause the video and frame advance through, I can see places were the subtitles are perfectly displayed, and places were they seem to have tears or something in the text. If I start play again on a location where the subtitles are displayed well, the video will continue to play all of the subtitles well. If I start play again on a location where the subtitles are torn, then all of the subtitles look like this (this is what I am calling shimmering). It appears that I see less of the tearing subs when I use a ref=1 rather than ref=3. I haven't been able to find any consistent repetition of good/bad sub display when stepping through the video. Usually (not always), the bad subtitles appear 4 frames in a row and then there will be good ones. The # of good sub frames between bad subs is not consistent though. I have tried baseline, main and high profiles as well as stepping through the presets from ultrafast to placebo. The profiles or the presets do not seem to affect the playback. I have tried the fastdecode and zerolatency tuning profiles, turning dct-decimate off, intra-refresh on, bframes off, trellis off, most all of the parameters on/off. I am looking for any ideas as to what the problem might be and any possible solutions (or thoughts). One other thing about H.264 playback on the TivoHD (in case it might somehow provide more information for a solution to the subtitle problem): initially, all h.264 encoded video would open with an initial green/blocky screen for the first few seconds. Muxing the audio stream in before the video stream in the mp4 container fixed this issue. If I use the same avs file and encode the video with HCenc, there are no playback issues. It appears to be a H.264 decode issue on the TivoHD. And just to reiterate, the x264 encoded files play fine on the computer just not the TivoHD. Source files are NTSC DVDs, ripped to hard drive, merged into 1 mpg with VideoRedo, and indexed with DGIndex with honor pulldown. My avs file is pretty simple. example.avs Code: loadplugin("D:\XviD4PSP5\apps\DGMPGDec\DGDecode.dll") loadplugin("D:\XviD4PSP5\dlls\AviSynth\plugins\TIVTC.dll") LoadPlugin("D:\XviD4PSP5\dlls\AviSynth\plugins\FluxSmooth.dll") LoadPlugin("D:\XviD4PSP5\dlls\AviSynth\plugins\Undot.dll") loadplugin("D:\XviD4PSP5\dlls\AviSynth\plugins\VSFilter.dll") MPEG2Source("D:\temp\x264\Rescue.Me.S2E07-clip.d2v",cpu=3) TFM().TDecimate() Undot().FluxSmoothT(3) Lanczos4resize(720,400) TextSub("D:\temp\x264\Rescue.Me.S2E07-clip.d2v.srt") x264 command line string that seems to play best (so far): Code: x264-r1416.exe --crf 18 --no-psy --keyint 24 --bframes 0 --sar 1:1 --ref 1 -o test.264 example.avs Could what I use to load the video in avisynth affect this? Or maybe the plugin used to display the subs (is there something beside vsfilter?)?