[FFmpeg-user] MPEG-2 encoding problem

Moritz Barsnick barsnick at gmx.net
Thu Feb 14 15:46:48 EET 2019

Hi Jane,

On Thu, Feb 14, 2019 at 21:14:07 +0800, Jane wrote:
>   Hello everyone! I'm encoding video to MPEG-2 using Zeranoe's Windows builds.  The source file is 720p 60fps, progressive. I want to keep high quality and compatibility with DVD standards, so I use:
> ffmpeg -hwaccel auto -i "input" -vf scale=ntsc,interlace,fps=fps=29.97 -c:v mpeg2video -q:v 3 -g 15 -mpeg_quant 1 -aspect 16:9 -sc_threshold 40 -bf 2 -intra_vlc 1 -b_stratgey 2 -flags ilme+ildct -maxrate 9M -bufsize 224k -c:a mp2 -b:a 224k "output"

For best assistance, we recommend to also post the complete, uncut
output of this ffmpeg command.

* " -b_stratgey 2" won't be accepted by ffmpeg, there's a typo in

* ffmpeg provides a set of defaults for maximum DVD compatibility,
  provided by "-target dvd". I wonder whether you really need to fiddle with
  any of the other parameters you provided.

  Here's what this "target" sets (from the source code):
        opt_video_codec(o, "c:v", "mpeg2video");
        opt_audio_codec(o, "c:a", "ac3"); // you can of course set mp2 instead // Moritz
        parse_option(o, "f", "dvd", options);

        parse_option(o, "s", norm == PAL ? "720x576" : "720x480", options);
        parse_option(o, "r", frame_rates[norm], options);
        parse_option(o, "pix_fmt", "yuv420p", options);
        opt_default(NULL, "g", norm == PAL ? "15" : "18");

        opt_default(NULL, "b:v", "6000000");
        opt_default(NULL, "maxrate:v", "9000000");
        opt_default(NULL, "minrate:v", "0"); // 1500000;
        opt_default(NULL, "bufsize:v", "1835008"); // 224*1024*8;

        opt_default(NULL, "packetsize", "2048");  // from www.mpucoder.com: DVD sectors contain 2048 bytes of data, this is also the size of one pack.
        opt_default(NULL, "muxrate", "10080000"); // from mplex project: data_rate = 1260000. mux_rate = data_rate * 8

        opt_default(NULL, "b:a", "448000");
        parse_option(o, "ar", "48000", options);

* As far as I understand, DVD supports progressive content just fine,
  so you can actually avoid interlacing (and requiring those flags).

* "-q:v 3" will result in quite low bandwith, IIRC. This may be one of
  your issues. Note how the defaults above specify a bandwidth, with a
  significant size. (If we saw your output, we could see which
  bandwidth your ffmpeg command resulted in. Probably much too low.)

> After disabled ildct and ilme, the quality is normal. Is the command incorrect?

That's interesting. Possibly, your "-flags" parameter is erasing other
flags. You should try "-flags +ilme+ildct". (Just a hunch, I'm not sure.)

> Due to the lack of information about codec mpeg2 video, I'm not sure
> about the sc_threshold, b_strategy and the dia_size value. How can i
> get detailed information?

Can't you just leave them at their/ffmpeg's defaults, if you don't know
what to do about them? Especially since you don't have knowledge of the
codec and their influences on it?

and let us know how it goes,

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