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  1. Member
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    Hi, I work at a tv station and I'm trying to reduce bitrates from 50i videos (top field first) for archive purposses.

    After many tests I have achieved x264 at 50i, top field first, but something is missing, maybe some data in the video header.

    Playing the video with VLC shows the wrong field order, bottom field first, and the image blinks (using Yadif 2x as deinterlace method).

    Playing the video in Edius, the video plays correctly, at 50i. But in the properties it says that it is "progressive". It must be "Top field first".

    This is the command I use:


    ffmpeg.exe -y -hide_banner -threads 0 -hwaccel dxva2 -i "ORIGINAL.MP4" -vcodec libx264 -profile:v high -preset slow -b:v 10000k -maxrate 10000k -s 1920x1080 -bufsize 30000k -flags +ilme+ildct -alternate_scan 1 -top 0 -acodec aac -b:a 128k -ar 44100 -movflags +faststart "RESULT.MP4" -vf yadif=1 -filter:v yadif


    I tried many combinations for ilme, yadif, top, etc... and this is what worked best for me. But with the problem of the field order indicator.

    The original video is 50i, top field first, and it plays correctly in VLC and in Edius.

    What do you think I might be doing wrong?

    Greetings.
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  2. Member
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    I tried with -top 1 and it solved the problem in VLC, it already does the de-interlacing correctly.

    But in Edius it still shows the video as progressive (but plays it well like top field first).
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  3. You have the yadif deinterlacer in your command. Twice. Why? You say you want to keep interlaced output.
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  4. After deinterlacing with Yadif your video is no longer interlaced, it's progressive. If you want to keep the video interlaced don't use Yadif. And VLC is borked -- it always plays interlaced AVC as BFF.
    Last edited by jagabo; 1st Jul 2020 at 10:21.
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  5. Member
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    Yes, Yadif was unnecessary, but apparently it had no effect, the resulting video was interlaced anyway.

    I removed it and the result is exactly the same, it plays correctly in VLC and in Edius, but in this one it is marked as "Progressive".

    It's like the video, with correct interlacing, had some incorrect information in the header.




    I copy the information from MediaInfo, in case it could be useful:

    This is the original video from a videocamera:

    Writing application : Sony PXW-X160

    Video
    ID : 4113 (0x1011)
    Menu ID : 1 (0x1)
    Format : AVC
    Format/Info : Advanced Video Codec
    Format profile : High@L4
    Format settings : CABAC / 2 Ref Frames
    Format settings, CABAC : Yes
    Format settings, RefFrames : 2 frames
    Format settings, GOP : M=2, N=13
    Codec ID : 27
    Duration : 22 s 800 ms
    Bit rate mode : Variable
    Bit rate : 21.4 Mb/s
    Maximum bit rate : 22.0 Mb/s
    Width : 1 920 pixels
    Height : 1 080 pixels
    Display aspect ratio : 16:9
    Frame rate : 25.000 FPS
    Color space : YUV
    Chroma subsampling : 4:2:0
    Bit depth : 8 bits
    Scan type : Interlaced
    Scan type, store method : Separated fields
    Scan order : Top Field First
    Bits/(Pixel*Frame) : 0.413
    Stream size : 58.1 MiB (89%)
    IrisFNumber : 1.700000







    And this is from the result FFmpeg file:

    riting application : Lavf58.45.100

    Video
    ID : 1
    Format : AVC
    Format/Info : Advanced Video Codec
    Format profile : High@L6.2
    Format settings : CABAC / 5 Ref Frames
    Format settings, CABAC : Yes
    Format settings, RefFrames : 5 frames
    Codec ID : avc1
    Codec ID/Info : Advanced Video Coding
    Duration : 22 s 880 ms
    Bit rate : 12.0 Mb/s
    Width : 1 920 pixels
    Height : 1 080 pixels
    Display aspect ratio : 16:9
    Frame rate mode : Constant
    Frame rate : 25.000 FPS
    Color space : YUV
    Chroma subsampling : 4:2:0
    Bit depth : 8 bits
    Scan type : MBAFF
    Scan type, store method : Interleaved fields
    Scan order : Top Field First
    Bits/(Pixel*Frame) : 0.231
    Stream size : 32.6 MiB (98%)
    Writing library : x264 core 160
    Encoding settings : cabac=1 / ref=5 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=8 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=2 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=24 / lookahead_threads=4 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=tff / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=0 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=50 / rc=cbr / mbtree=1 / bitrate=12000 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / vbv_maxrate=12000 / vbv_bufsize=36000 / nal_hrd=none / filler=0 / ip_ratio=1.40 / aq=1:1.00
    Codec configuration box : avcC



    Perhaps is relative to MBAFF and the store method?


    Also, FFMpeg gives me these errors:

    [libx264 @ 000001d2b8abb800] interlace + weightp is not implemented
    [libx264 @ 000001d2b8abb800] interlaced (1) > level limit (0)
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  6. Seems basically correct to me.
    - Your source is interlaced.
    - Your encode is also interlaced (MBAFF, Interlaeaved fields), TFF.
    What is the problem?

    Error messages:
    You can ignore the first message. It's just a hint that x264 does not support weight p for interlaced encoding.
    Second message: You set the format profile High/Level 6.2. -> Reduce the level to 4.0 or 4.1
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  7. Member
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    I added -level 4.1 and it was fixed, thank you.

    I also added -g 50 for faster editing.

    The problem is that Edius marks the videos as progressive, even they are interlaced and play correctly.

    It doesn't seem important but it's about transcoding a lot of TB of videos and I don't want to have problems in the future if we use other applications.

    Thanks to all.
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