Remove letterboxing from 16:9 video (and now other encode questions)

[CDickey370]

Hello, I have an mpeg2 file that Quicktime info states is 640x480. The video was captured from an HD broadcast source using s-video so it is 1.85:1 with letterboxing. Is there a way to remove the letterboxing from the video?

I want to be able to burn it onto DVD and display properly on my widescreen HDTV.

[Case]

Hello, I have an mpeg2 file that Quicktime info states is 640x480.

QuickTime Player will tell the resolution of the default display, which is quite often not the native resolution with MPEG-1/-2 files, but (down)scaled and optically 'corrected' for display (because of non-square pixels).
For the real resolution of your source file, use another tool, e.g the left side of the Summary tab in ffmpegX.

Is there a way to remove the letterboxing from the video?

Calculate how many pixels you need to remove of the native resolution, then use those numbers in the Crop section of the Filters tab. Or try the Autocrop feature.

[CDickey370]

left side of the summary tab in ffmpegX says 720x480

[Case]

Use the 'DVD (ffmpeg)' preset. Go to the Video tab, change Autosize to 'DVD 16:9'. Go to the Filters tab, set the Preview time to a time in the video where the letterboxing is obvious (i.e. not a total black screen), so that the Autocrop can figure out where the bars are. The default 30 sec is often good. Press Autocrop, it will automaticly fill the boxes. Check the numbers, my guess is around 60 pixels. Go to the options tab, check the boxes you need, but don't check 'Decode with Quicktime', as it will darken the output, in my experience. Hit encode, go find a new activity for a couple of hours.
It should go from this to that:

[CDickey370]

Excellent. OK, final question not related to this topic. What options do you suggest for best encoding? I'd like this to look it's best.

[Case]

For DVD encoding, I'd use High Quality, Use B-frames, 4 motion vectors and Trellis quantization (briefly explained on the website). This requires more computation, thus longer encoding time, than not using these options.
If you have disc space to spare, you could also try a higher bitrate and a lower Qmax.
But these option will not eliminate the slight fuzziness caused by the upscaling.

[CDickey370]

Thank you.

[CDickey370]

OK, so I lied... one more issue, I appreciate the help.

I went to do a new encoding with the suggested settings for better quality, using the ffmpeg preset, select DVD 16:9 and all that you told me to do. However, this time the resulting video has letterboxing and the video is stretched to 16:9.

I looked at the info of the previous encode that worked and compared it to the info on the new attempt. The previous encoded shows that somehow (I didnt change it) video size had been changed to 704x528.

Do you know why this would have changed, why it would work properly, what effect it will have on the encode (quality wise) and why the default 720x480 did not work in cropping the letterboxing?

[Case]

I tried to duplicate this, and also got that result. Same for VCD, SVCD and DVD targets using the ffmpeg engine. (a) Autocrop changes the videosize to 704x528, regardless of previous size values or crop values. (b) The crop setting is ignored; black bars are included in the output file. Even multiples of 16 [80,80,0,0] make no difference.

DivX (ffmpeg) works with crop, however, so it's not the ffmpeg engine per se.

Maybe major can shed some light on this?

[CDickey370]

Yep, hopefully Major can share some insight.

Oh, and is it normal for Quicktime to not be able to play the AC3 audio from the resulting mpeg file yet VLC can?

[Ai Haibara]

I believe you need an AC3 Quicktime component installed before it can play AC3 audio in a movie.

[CDickey370]

Ok I really lied about last question. In addition to previous questions can you explain what this is? I get multiple lines of it when encoding.

mpeg2video @ 0x444b70]rc buffer underflow3 bitrate=4103.5kbits/s
[mpeg2video @ 0x444b70]rc buffer underflow
[mpeg2video @ 0x444b70]rc buffer underflow
[mpeg2video @ 0x444b70]rc buffer underflow
[mpeg2video @ 0x444b70]rc buffer underflow
[mpeg2video @ 0x444b70]rc buffer underflow
[mpeg2video @ 0x444b70]rc buffer underflow
[mpeg2video @ 0x444b70]rc buffer underflow

and

++ WARN: [mplex] Stream e0: data will arrive too late sent(SCR)=7213789 required(DTS)=7213725
++ WARN: [mplex] Video e0: buf= 194967 frame=002397 sector=00020197
++ WARN: [mplex] Audio bd: buf= 15043 frame=002499 sector=00002222
++ WARN: [mplex] Stream bd: data will arrive too late sent(SCR)=7266327 required(DTS)=7253097
++ WARN: [mplex] Video e0: buf= 237568 frame=002411 sector=00020485
++ WARN: [mplex] Audio bd: buf= 14368 frame=002513 sector=00002234
++ WARN: [mplex] Discarding incomplete final frame AC3 stream 0!
**ERROR: [mplex] MUX STATUS: Frame data under-runs detected!

[major]

I tried to duplicate this, and also got that result. Same for VCD, SVCD and DVD targets using the ffmpeg engine. (a) Autocrop changes the videosize to 704x528, regardless of previous size values or crop values. (b) The crop setting is ignored; black bars are included in the output file. Even multiples of 16 [80,80,0,0] make no difference.

DivX (ffmpeg) works with crop, however, so it's not the ffmpeg engine per se.

Maybe major can shed some light on this?

Indeed, for now when "Decode with Quicktime" is used, cropping is not supported. Also cropping for VCD/SVCD/DVD is only available with ffmpeg engine (mpeg2enc doesn't support it directly).

[CDickey370]

I didn't have Decode with Quicktime checked and cropping still did not occur.

[major]

Could you please email me to major4@mac.com a clip and a preset file? Thank you

[Case]

Cropping mpeg-2 to mpeg-2 (ffmpeg, no qt) now works with 0.0.9w, yay!

[upekshapriya]

I'm also a problem with cropping.

I am trying to remove side pllars from a 16:9 .mov file (of a 4:3 TV prog) and convert to a 4:3 .mp4 to view on my iPod (320x240) but the black pillars are not removed even with 'Decode with Quicktime' unticked. I end up getting the original file sqashed into 4:3.

However it's difficult to imagine how it is going to be decoded without Quicktime being as it is a Quicktime file.

Any ideas?

[Case]

What are the video and audio codecs in your .mov file?
What is the video size of your .mov file?
What are the crop values that you used to remove the pillars?
Some .mov files can be read without QuickTime. It depends on the specs.

[upekshapriya]

Thanks for such a prompt reply. The video details (from mediainfo on Windows) are:

General

Complete name : movie.mov

Format : MPEG-4

Format profile : QuickTime

Codec ID : qt

File size : 12.1 MiB

Duration : 3mn 16s

Overal bit rate : 518 Kbps

Encoded date : UTC 1970-01-01 00:00:00

Tagged date : UTC 1970-01-01 00:00:00

Writing application : Lavf52.7.0

Comment : QuickTime 6.0 or greater



Video

Format : AVC

Format/Info : Advanced Video Codec

Format profile : Baseline@L3.0

Format settings, CABAC : No

Format settings, ReFrames : 1

Codec ID : avc1

Duration : 3mn 16s

Bit rate mode : VBR

Bit rate : 398 Kbps

Width : 480 pixels

Height : 272 pixels

Display aspect ratio : 16/9

Frame rate mode : CFR

Frame rate : 25.000 fps

Colorimetry : 4:2:0

Scan type : Progressive

Bits/(Pixel*Frame) : 0.122

Stream size : 9.33 MiB

Encoded date : UTC 1970-01-01 00:00:00

Tagged date : UTC 1970-01-01 00:00:00



Audio

Format : AAC

Format/Info : Advanced Audio Codec

Format version : Version 4

Format profile : LC

Format settings, SBR : No

Duration : 3mn 15s

Bit rate mode : VBR

Bit rate : 116 Kbps

Channel(s) : 2 channels

Channel positions : L R

Sampling rate : 48.0 KHz

Resolution : 16 bits

Stream size : 2.71 MiB

Encoded date : UTC 1970-01-01 00:00:00

Tagged date : UTC 1970-01-01 00:00:00



The crop values which were collected by auto crop are 0 0 66 62

After specifying a video of dimensions 320 x 240 I get a video of 352 x 256 with the black pillars still there. I am using the option of 'Decode with Quicktime' unchecked.

I saved a preset of my settings. Here is the text extracted:

ffmpegX Preset File
_version=14

_encoder=x264
_video=true
_videoformat=21
_width=320
_height=240
_ratio=8
_videobitrate=768
_framerate=PAL (25)

_iframes=250
_minq=10
_maxq=51
_level=3
_cabac=false
_bframes=false
_twopass=false
_constant=true
_motionestimation=1
_i4x4=true
_trellis=false
_profile=2_qtdecode=false
_denoise=false
_deinterlace=false
_dering=false
_deblock=true
_brightness=0
_contrast=0

_croptop=0
_cropbottom=0
_cropleft=66
_cropright=62

_audio=true
_audioformat=6
_audiobitrate=96
_audiosampling=48000
_audiogain=0
_audiochannels=0
_audiomode=0
_invertmap=false

Any ideas what's happening?

[Case]

Any ideas what's happening?

It appears the x264 encoder doesn't support cropping - never realized that until I just tested it. You might go with XviD [MP4] (ffmpeg) video, which does support cropping.

[upekshapriya]

Thanks for your testing, though I'll have to choose iPod MPEG-4 so it will play on my iPod. I'll do another test later.