First off: I have done a websearch to no avail. I have also searched on linuxquestions.org, also, to no avail.

SOME of my videos, only of MKV, do not display them as video, only as audio, when using Smplayer (currently using version 14.9.0~ds0-1) (on Debian Stable (version 8.7))

They play as normal using VLC, but I would rather use Smplayer.

Why cannot I use Smplayer on all MKV videos?

It is not a major problem, more of a minor irritation. Does anyone have any advice?

Thank you for any responses, and have a good day.

please have a look at the backend smplayer is using, then do some troubleshooting with the backend only. can you reproduce the problem?
in any case you should get useful terminal output.

also, more information on which files work as expected and which don't.

1 members found this post helpful.

OK, the back-end is "mplayer2".

I get the same result on mplayer2 as with smplayer.

the two test files are:
BAD: Farscape S01E02.mkv
GOOD: The.Thing.mkv

{actually, none of the Farscape videos work on smplayer, but do work on VLC}

For your amusement, I will include log files from GOOD and BAD on smplayer

GOOD:

// begin =====================================================================================

/usr/bin/mplayer -noquiet -nofs -nomouseinput -sub-fuzziness 1 -identify -slave -vo xv -ao pulse -nokeepaspect -nodr -double -input nodefault-bindings:conf=/dev/null -stop-xscreensaver -wid 67108959 -monitorpixelaspect 1 -ass -embeddedfonts -ass-line-spacing 0 -ass-font-scale 1 -ass-styles /home/kevin/.config/smplayer/styles.ass -subfont-autoscale 0 -subfont-text-scale 20 -subcp ISO-8859-1 -subpos 100 -volume 100 -cache 2048 -osdlevel 0 -vf-add screenshot -noslices -channels 2 -af volnorm=1,scaletempo,equalizer=0:0:0:0:0:0:0:0:0:0 -softvol -softvol-max 100 /home/VDO/The.Thing.1982.BluRay.720p.x264.YIFY.mkv

MPlayer2 2.0-728-g2c378c7-4+b1 (C) 2000-2012 MPlayer Team
Terminal type `unknown' is not defined.

Playing /home/VDO/The.Thing.1982.BluRay.720p.x264.YIFY.mkv.
Cache size set to 2048 KiB

Cache fill: 0.00% (0 bytes)
ID_VIDEO_ID=0
ID_VID_0_NAME=The Thing - YIFY
[mkv] Track ID 1: video (V_MPEG4/ISO/AVC) "The Thing - YIFY", -vid 0
ID_AUDIO_ID=0
ID_AID_0_NAME=The Thing - YIFY
ID_AID_0_LANG=und
[mkv] Track ID 2: audio (A_AAC) "The Thing - YIFY", -aid 0, -alang und
ID_SUBTITLE_ID=0
ID_SID_0_NAME=The Thing - YIFY
ID_SID_0_LANG=eng
[mkv] Track ID 3: subtitles (S_TEXT/UTF8) "The Thing - YIFY", -sid 0, -slang eng
[mkv] Will play video track 1.
Detected file format: Matroska
Load subtitles in /home/VDO/
ID_FILENAME=/home/VDO/The.Thing.1982.BluRay.720p.x264.YIFY.mkv
ID_DEMUXER=mkv
ID_VIDEO_FORMAT=avc1
ID_VIDEO_BITRATE=0
ID_VIDEO_WIDTH=1280
ID_VIDEO_HEIGHT=544
ID_VIDEO_FPS=23.976
ID_VIDEO_ASPECT=2.3529
ID_AUDIO_FORMAT=MP4A
ID_AUDIO_BITRATE=0
ID_AUDIO_RATE=24000
ID_AUDIO_NCH=2
ID_START_TIME=0.00
ID_LENGTH=6522.54
ID_SEEKABLE=1
ID_CHAPTERS=0
[ass] auto-open
Opening video filter: [screenshot]
Selected video codec: H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 [libavcodec]
ID_VIDEO_CODEC=ffh264
Selected audio codec: AAC (Advanced Audio Coding) [libavcodec]
AUDIO: 48000 Hz, 2 ch, floatle, 128.0 kbit/4.17% (ratio: 16000->384000)
ID_AUDIO_BITRATE=128000
ID_AUDIO_RATE=48000
ID_AUDIO_NCH=2
AO: [pulse] 48000Hz 2ch floatle (4 bytes per sample)
ID_AUDIO_CODEC=ffaac
[Mixer] No hardware mixing, inserting volume filter.
Starting playback...
VIDEO: 1280x544 23.976 fps 0.0 kbps ( 0.0 kB/s)
ID_VIDEO_ASPECT=2.3529
VO: [xv] 1280x544 => 1280x544 Planar YV12

// end =====================================================================================

BAD:

// begin =====================================================================================

/usr/bin/mplayer -noquiet -nofs -nomouseinput -sub-fuzziness 1 -identify -slave -vo xv -ao pulse -nokeepaspect -nodr -double -input nodefault-bindings:conf=/dev/null -stop-xscreensaver -wid 90177631 -monitorpixelaspect 1 -ass -embeddedfonts -ass-line-spacing 0 -ass-font-scale 1 -ass-styles /home/kevin/.config/smplayer/styles.ass -subfont-autoscale 0 -subfont-text-scale 20 -subcp ISO-8859-1 -aid 0 -subpos 100 -volume 100 -cache 2048 -ss 63 -osdlevel 0 -vf-add screenshot -noslices -channels 2 -af volnorm=1,scaletempo,equalizer=0:0:0:0:0:0:0:0:0:0 -softvol -softvol-max 100 /home/kevin/Desktop/Farscape/Farscape Season 1/Farscape S01E02 Exodus from Genesis (1080p x265 Joy).mkv

MPlayer2 2.0-728-g2c378c7-4+b1 (C) 2000-2012 MPlayer Team
Terminal type `unknown' is not defined.

Playing /home/kevin/Desktop/Farscape/Farscape Season 1/Farscape S01E02 Exodus from Genesis (1080p x265 Joy).mkv.
Cache size set to 2048 KiB

Cache fill: 0.00% (0 bytes)
[mkv] Unknown/unsupported CodecID (V_MPEGH/ISO/HEVC) or missing/bad CodecPrivate
[mkv] data (track 1).
[mkv] Track ID 1: video (V_MPEGH/ISO/HEVC), -vid 0
ID_AUDIO_ID=0
ID_AID_0_NAME=Surround
ID_AID_0_LANG=und
[mkv] Track ID 2: audio (A_AAC) "Surround", -aid 0, -alang und
ID_SUBTITLE_ID=0
ID_SID_0_LANG=fre
[mkv] Track ID 3: subtitles (S_TEXT/ASS), -sid 0, -slang fre
ID_SUBTITLE_ID=1
ID_SID_1_LANG=eng
[mkv] Track ID 4: subtitles (S_TEXT/ASS), -sid 1, -slang eng
[mkv] No video track found/wanted.
Detected file format: Matroska
Clip info:
CREATION_TIME:
ID_CLIP_INFO_NAME0=CREATION_TIME
ID_CLIP_INFO_VALUE0=
ENCODER: Lavf55.12.0
ID_CLIP_INFO_NAME1=ENCODER
ID_CLIP_INFO_VALUE1=Lavf55.12.0
ID_CLIP_INFO_N=2
Load subtitles in /home/kevin/Desktop/Farscape/Farscape Season 1/
ID_FILENAME=/home/kevin/Desktop/Farscape/Farscape Season 1/Farscape S01E02 Exodus from Genesis (1080p x265 Joy).mkv
ID_DEMUXER=mkv
ID_AUDIO_FORMAT=MP4A
ID_AUDIO_BITRATE=0
ID_AUDIO_RATE=24000
ID_AUDIO_NCH=6
ID_START_TIME=0.00
ID_LENGTH=3010.11
ID_SEEKABLE=1
ID_CHAPTERS=0
Selected audio codec: AAC (Advanced Audio Coding) [libavcodec]
AUDIO: 48000 Hz, 6 ch, floatle, 128.0 kbit/1.39% (ratio: 16000->1152000)
ID_AUDIO_BITRATE=128000
ID_AUDIO_RATE=48000
ID_AUDIO_NCH=6
AO: [pulse] 48000Hz 2ch floatle (4 bytes per sample)
ID_AUDIO_CODEC=ffaac
[Mixer] No hardware mixing, inserting volume filter.
Video: no video
Starting playback...


// end =====================================================================================

Unfortunately, I cannot interpret much of these logs.

BUT it seems to me that some MKV files run under different codecs than others. IF that is the case, how can I re-"compile" the "bad" files to "good" files?

Thank you for your help, and have a good day.

OK, here is the output from mplayer2

It is a typescript, first GOOD then BAD

Script started on Sun 26 Feb 2017 08:04:30 AM CST
]0;kevin@Shatner: ~kevin@Shatner:~$ mplayer /home/VDO/Equilibrium.2002.720p.BrRip.x264.YIFY.mkv
kevin/Desktop/Farscape/Farscape\ Season\ 1/Farscap
pe\ S01E02\ Exodus\ from\ Genesis\ \(1080p\ x265\ Joy\).mkv
MPlayer2 2.0-728-g2c378c7-4+b1 (C) 2000-2012 MPlayer Team
Cannot open file '/home/kevin/.mplayer/input.conf': No such file or directory
Failed to open /home/kevin/.mplayer/input.conf.
Cannot open file '/etc/mplayer/input.conf': No such file or directory
Failed to open /etc/mplayer/input.conf.

Playing /home/kevin/Desktop/Farscape/Farscape Season 1/Farscape S01E02 Exodus from Genesis (1080p x265 Joy).mkv.
[mkv] Unknown/unsupported CodecID (V_MPEGH/ISO/HEVC) or missing/bad CodecPrivate
[mkv] data (track 1).
[mkv] Track ID 1: video (V_MPEGH/ISO/HEVC), -vid 0
[mkv] Track ID 2: audio (A_AAC) "Surround", -aid 0, -alang und
[mkv] Track ID 3: subtitles (S_TEXT/ASS), -sid 0, -slang fre
[mkv] Track ID 4: subtitles (S_TEXT/ASS), -sid 1, -slang eng
[mkv] No video track found/wanted.
Detected file format: Matroska
Clip info:
CREATION_TIME:
ENCODER: Lavf55.12.0
Load subtitles in /home/kevin/Desktop/Farscape/Farscape Season 1/
Selected audio codec: AAC (Advanced Audio Coding) [libavcodec]
AUDIO: 48000 Hz, 6 ch, floatle, 128.0 kbit/1.39% (ratio: 16000->1152000)
AO: [pulse] 48000Hz 2ch floatle (4 bytes per sample)
Video: no video
Starting playback...
A: -0.0 (unknown) of 3010.1 (50:10.1) 2.0% 
A: 0.0 (00.0) of 3010.1 (50:10.1) 1.9% 

*** deleting crap ***

Exiting... (Quit)
]0;kevin@Shatner: ~kevin@Shatner:~$ mplayer /home/kevin/Desktop/Farscape/Farscape\ Season\ 1/Farscap
pe\ S01E02\ Exodus\ from\ Genesis\ \(1080p\ x265\ Joy\).mkv VDO/Equilibrium.2002.720p.BrRip.x264.YIFY.mkv


MPlayer2 2.0-728-g2c378c7-4+b1 (C) 2000-2012 MPlayer Team
Cannot open file '/home/kevin/.mplayer/input.conf': No such file or directory
Failed to open /home/kevin/.mplayer/input.conf.
Cannot open file '/etc/mplayer/input.conf': No such file or directory
Failed to open /etc/mplayer/input.conf.

Playing /home/VDO/Equilibrium.2002.720p.BrRip.x264.YIFY.mkv.
[mkv] Track ID 1: video (V_MPEG4/ISO/AVC) "Equilibrium - YIFY", -vid 0
[mkv] Track ID 2: audio (A_AAC) "Equilibrium - YIFY", -aid 0, -alang und
[mkv] Track ID 3: subtitles (S_TEXT/UTF8) "Equilibrium - YIFY", -sid 0, -slang eng
[mkv] Will play video track 1.
Detected file format: Matroska
Load subtitles in /home/VDO/
Selected video codec: H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 [libavcodec]
Selected audio codec: AAC (Advanced Audio Coding) [libavcodec]
AUDIO: 48000 Hz, 2 ch, floatle, 128.0 kbit/4.17% (ratio: 16000->384000)
AO: [pulse] 48000Hz 2ch floatle (4 bytes per sample)
Starting playback...
VIDEO: 1280x544 23.976 fps 0.0 kbps ( 0.0 kB/s)
VO: [vdpau] 1280x544 => 1280x544 Planar YV12
[vdpau] Compositing window manager detected. Assuming timing info is inaccurate.
A: -0.0 V: 0.0 A-V: -0.001 ct: 0.000 0/ 0 ??% ??% ??,?% 0 0 
A: 0.0 V: 0.0 A-V: 0.000 ct: 0.000 0/ 0 ??% ??% ??,?% 0 0 


*** deleting crap ***


Exiting... (Quit)
]0;kevin@Shatner: ~kevin@Shatner:~$ exit
exit

Script done on Sun 26 Feb 2017 08:04:55 AM CST

The "Good" file you are using is an h.264/AVC file.

The "Bad" file you are using is an h.265/HEVC file.

The smplayer backend you are trying to use (mplayer2) is not built with h.265/HEVC support. In fact, mplayer2 is basically a dead end. Install/use mpv as the backend if possible. smplayer added support for mpv backend a couple of years ago, but I have no idea if that version made it into Debian 8 or not.

1 members found this post helpful.

I installed "mpv" but I cannot get smplayer to use it as a backend for smplayer.

I used handbrake (aka "ghb") to read a "bad" mkv file, and write a "good" mkv file, such that it displays it as a video.
BUT, it uses a butt-load of processor power, a bunch of time, and the end file size is approximately 150% of the original file. At this rate, it would take a better part of a day to process a single season.

PS: I have an 8-core processor, and 16 gigabytes of memory, so my computer is, in no way, under powered.
If I find no solution, I guess I may have to "suck it up" and start using VLC as my video client.

Thank you for your help, and have a good day.

as it was already mentioned, it is a codec related problem. VLC is able to play/recognize your video, the other player could not handle that codec.
Probably handbrake can convert the video for you, I have no idea about that. Usually conversion needs a lot of resources, file size highly depends on the compression ratio of the codec you use, so in general 150% can be acceptable too.

1 members found this post helpful.

Yeah, it turns out that the version of smplayer in Debian 8/jessie repo is too old for mpv: https://bugs.debian.org/cgi-bin/bugr...cgi?bug=783401

So, you can try to build a newer version of smplayer, or try their pre-built .deb: https://software.opensuse.org/downlo...ckage=smplayer

1 members found this post helpful.

OK, I will try installing an updated version.

Before my stroke, I had used a mix of testing/unstable version of Debian. But after the stroke, I had messed up my system and had to do a reinstall, and I switched to Stable. So, I will, CAREFULLY, install the appropriate newer version.

Thank you for your help in this matter,
and have a good day!

OK.

I installed the newer version of smplayer, made the appropriate change in smplayer, and it now works.... FINALLY!!!

Seasons: You have been helpful to me, thank you for your time and attention to my minor irritations. You are a gentleman and a scholar.

And thank you to everyone who has given me advice.

Have a good day!