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  1. Member
    Join Date: Jan 2014
    Location: United Kingdom
    Search PM
    Hi,

    I am new to this forum and I am here to understand a bit more about the encoding technology, which I find quite intriguing. The intriguing bit is how apparently random the performance on devices is. To simplify the matter, I will say I have a 2009 Samsung TV that can decode video it fetches from a USB stick. Recently, I played a pretty massive bitrate video on it and it played it smoothly. I analysed the file with MediaInfo and this is what it says about it.


    General
    Format : MPEG-4
    Format profile : Base Media / Version 2
    Codec ID : mp42
    File size : 474 MiB
    Duration : 2mn 18s
    Overall bit rate mode : Variable
    Overall bit rate : 28.7 Mbps
    Encoded date : UTC 2011-12-05 22:00:22
    Tagged date : UTC 2011-12-05 22:00:22
    ęTIM : 00:00:00:00
    ęTSC : 24000
    ęTSZ : 1001


    Video
    ID : 1
    Format : AVC
    Format/Info : Advanced Video Codec
    Format profile : High@L5.1
    Format settings, CABAC : Yes
    Format settings, ReFrames : 3 frames
    Codec ID : avc1
    Codec ID/Info : Advanced Video Coding
    Duration : 2mn 18s
    Bit rate mode : Constant
    Bit rate : 28.4 Mbps
    Nominal bit rate : 30.0 Mbps
    Width : 1 920 pixels
    Height : 1 080 pixels
    Display aspect ratio : 16:9
    Frame rate mode : Constant
    Frame rate : 23.976 fps
    Standard : NTSC
    Color space : YUV
    Chroma subsampling : 4:2:0
    Bit depth : 8 bits
    Scan type : Progressive
    Bits/(Pixel*Frame) : 0.571
    Stream size : 469 MiB (99%)
    Language : English
    Encoded date : UTC 2011-12-05 22:00:22
    Tagged date : UTC 2011-12-05 22:00:22
    Color primaries : BT.709
    Transfer characteristics : BT.709
    Matrix coefficients : BT.709


    Audio
    ID : 2
    Format : AAC
    Format/Info : Advanced Audio Codec
    Format profile : LC
    Codec ID : 40
    Duration : 2mn 18s
    Source duration : 2mn 18s
    Bit rate mode : Variable
    Bit rate : 317 Kbps
    Maximum bit rate : 410 Kbps
    Channel(s) : 2 channels
    Channel positions : Front: L R
    Sampling rate : 48.0 KHz
    Compression mode : Lossy
    Stream size : 5.24 MiB (1%)
    Source stream size : 5.24 MiB (1%)
    Language : English
    Encoded date : UTC 2011-12-05 22:00:22
    Tagged date : UTC 2011-12-05 22:00:22



    Now, interestingly enough, I have some footage recorded with a GoPro and I wanted to reduce it to a more manageable size. I used handbrake to do that and I tried several quality parameters. Although the bitrate is a lot lower (3Mbps), my TV struggles to decode the video and misses some frames. Here are the details of the file I am talking about.


    General
    Format : MPEG-4
    Format profile : Base Media / Version 2
    Codec ID : mp42
    File size : 337 MiB
    Duration : 14mn 9s
    Overall bit rate mode : Variable
    Overall bit rate : 3 330 Kbps
    Encoded date : UTC 2014-01-15 20:15:37
    Tagged date : UTC 2014-01-15 22:24:50
    Writing application : HandBrake 0.9.9 2013052900


    Video
    ID : 1
    Format : AVC
    Format/Info : Advanced Video Codec
    Format profile : High@L4.1
    Format settings, CABAC : Yes
    Format settings, ReFrames : 4 frames
    Codec ID : avc1
    Codec ID/Info : Advanced Video Coding
    Duration : 14mn 9s
    Bit rate : 3 195 Kbps
    Width : 1 920 pixels
    Height : 1 080 pixels
    Display aspect ratio : 16:9
    Frame rate mode : Variable
    Frame rate : 50.000 fps
    Minimum frame rate : 28.571 fps
    Maximum frame rate : 50.000 fps
    Color space : YUV
    Chroma subsampling : 4:2:0
    Bit depth : 8 bits
    Scan type : Progressive
    Bits/(Pixel*Frame) : 0.031
    Stream size : 324 MiB (96%)
    Writing library : x264 core 130 r2273 b3065e6
    Encoding settings : cabac=1 / ref=4 / deblock=1:0:0 / analyse=0x3:0x113 / me=umh / subme=8 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=3 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=500 / keyint_min=50 / scenecut=40 / intra_refresh=0 / rc_lookahead=50 / rc=crf / mbtree=1 / crf=23.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / vbv_maxrate=62500 / vbv_bufsize=78125 / crf_max=0.0 / nal_hrd=none / ip_ratio=1.40 / aq=1:1.00
    Encoded date : UTC 2014-01-15 20:15:37
    Tagged date : UTC 2014-01-15 22:24:50
    Color primaries : BT.709
    Transfer characteristics : BT.709
    Matrix coefficients : BT.709


    Audio
    ID : 2
    Format : AAC
    Format/Info : Advanced Audio Codec
    Format profile : LC
    Codec ID : 40
    Duration : 14mn 9s
    Bit rate mode : Variable
    Bit rate : 128 Kbps
    Maximum bit rate : 132 Kbps
    Channel(s) : 2 channels
    Channel positions : Front: L R
    Sampling rate : 48.0 KHz
    Compression mode : Lossy
    Stream size : 13.0 MiB (4%)
    Language : English
    Encoded date : UTC 2014-01-15 20:15:37
    Tagged date : UTC 2014-01-15 22:24:49



    I got really curious about this thing. Although the TV has less data process, it struggles a lot more. Does anyone have an idea of why this may be happening? Ultimately, I would like to be able to re-encode this video in a way that does not make my TV decoder suffer. Do you have any suggestions? I've found out already that with pretty much the same parameters but a lower quality setting, the problem disappears, but the video becomes quite poor. The first video demonstrates that my TV can play stunning content if it's encoded the right way, so I would like to understand.


    Thanks!
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  2. Member
    Join Date: Mar 2008
    Location: United States
    Search Comp PM
    Perhaps the TV does not like the 50 frames per second @ 1080p. Have you played this kind of file successfully before?
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  3. Member
    Join Date: Jan 2014
    Location: United Kingdom
    Search PM
    Honestly, I don't know! Probably not off a USB stick anyway. Would you recommend trying to re-encode it at 25 or is it a blasphemy quality-wise? Forgive my ignorance?
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  4. Member
    Join Date: Nov 2003
    Location: West Texas
    Search PM
    Some devices don't like variable frame rate either.
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  5. Hoover Fanatic budwzr's Avatar
    Join Date: Apr 2007
    Location: City Of Angels
    Search Comp PM
    You might try playing it through a ChromeCast dongle ($35), into your HDMI. The USB stick may be slow.
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  6. Member
    Join Date: Jan 2004
    Location: UK
    Search Comp PM
    Originally Posted by davexnet View Post
    Perhaps the TV does not like the 50 frames per second @ 1080p. Have you played this kind of file successfully before?
    I think you've hit the nail on the head there....there are still relatively few TVs or media players that will guarantee to play 1080/50p (or 60p for those on the other side of the pond!). So a 6 year old TV will almost certainly find 1080/50p material a problem.Two options really.... drop the resolution to 720/50p, or keep it at 1080, and drop the frame rate to 25.
    You lose some quality with either option.
    I prefer to keep the 50p and go to 720. Not everyone does....
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  7. Most media players seem to support High Profile 4.1, which only allows for 50p/60p up to a 720p resolution. Any 50p/60p support for higher resolutions would be a bonus. And yeah, I'd probably play it safe and select a constant output frame rate.
    I wonder what the original frame rate was for the second video? Handbrake (I think) tends to vary the frame rate as part of the IVTC process, but I've never quite got my head around how it works (I don't use Handbrake myself).

    The first video is High Profile, 5.1, which the TV probably doesn't support, but the number of reference frames is fairly low, so the TV's behaving and playing the video rather than not checking it properly and refusing.
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  8. Member Cornucopia's Avatar
    Join Date: Oct 2001
    Location: Deep in the Heart of Texas
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    Originally Posted by Kerry56 View Post
    Some devices don't like variable frame rate either.
    Make that MOST and you are closer to your answer.

    VFR is a bad solution to an essentially nonexistent problem that often brings with it serious side effects. IMO, it should almost NEVER be used.

    Scott
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  9. Yes, 1080p50 and VFR is beyond the capabilities of most TVs and standalone media players. Converting to 720p50 will keep fluid motion but reduce resolution. Converting to 1080p25 will lose fluid motion but keep resolution. Take your pick. Or wait a few years and buy a new TV/player.
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  10. Whatever you do to "fix" this video, may not be necessary on a different playback device, may look worse on a different device, or may not work at all.

    The real solution is to use a standardized playback device, rather than chase various system's capabilities. A PC will play virtually anything you can throw at it. Many standalone media players come close to that standard. TV's seem to be fairly erratic in what they will, and will not, support.
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  11. Member
    Join Date: Jan 2014
    Location: United Kingdom
    Search PM
    Thank you all for your replies. I agree that chasing my TV's capabilities is not the right thing to do. However, I wanted to understand more about encoding and thanks to your help I did.For the record, the constant bit rate didn't help... reducing the frame rate to 25 fps, however, did the trick. The videos themselves are not particularly good quality (which is why I want to re-encode them anyway... they're not worth the amount of storage they demand). I just wanted to understand more about my encoding parameters before deleting the original files!
    Thank you all again.
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