I tried http://www.kdenlive.org/dnxhd-1920x1080-220-mbs and I hear the sound, but I don't see a video.

s=1920x1080 aspect=@16/9 b=220000k vcodec=dnxhd acodec=pcm_s16le
was modified to
s=1024x568 aspect=@16/9 b=220000k vcodec=dnxhd acodec=libmp3lame ab=256k ar=44100 ac=2

I tried too:
f=mov acodec=libmp3lame ab=256k ar=44100 ac=2 vcodec=dnxhd qscale=1 aspect=%dar

and is the same, there is no video, but sound.

mediainfo doesn't show a videoport.

What's wrong?

Source:
mediainfo test.mkv
General
Unique ID : 30065369223496152199292532958166510834 (0x169E61261A6C7E41CF48EDD68657ECF2)
Complete name : test.mkv
Format : Matroska
Format version : Version 2
File size : 28.3 MiB
Duration : 20s 760ms
Overall bit rate mode : Variable
Overall bit rate : 11.4 Mbps
Writing application : HandBrake 4394svn
Writing library : libmkv 0.6.5

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L3.0
Format settings, CABAC : Yes
Format settings, ReFrames : 4 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 20s 760ms
Width : 736 pixels
Height : 416 pixels
Display aspect ratio : 16:9
Frame rate mode : Variable
Frame rate : 25.000 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Writing library : x264 core 119
Encoding settings : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=7 / 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=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=1 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=50 / rc=crf / mbtree=1 / crf=12.0 / qcomp=0.60 / qpmin=3 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Language : English
Color primaries : BT.601-6 525, BT.1358 525, BT.1700 NTSC, SMPTE 170M
Transfer characteristics : BT.709-5, BT.1361
Matrix coefficients : BT.601-6 525, BT.1358 525, BT.1700 NTSC, SMPTE 170M

Audio
ID : 2
Format : FLAC
Format/Info : Free Lossless Audio Codec
Codec ID : A_FLAC
Duration : 20s 760ms
Bit rate mode : Variable
Channel(s) : 2 channels
Sampling rate : 44.1 KHz
Bit depth : 16 bits

DNxHD codec is limited to resolutions of 1920x1080 or 1280x720
This works for me:

s=1280x720 aspect=@16/9 b=220000k vcodec=dnxhd acodec=libmp3lame ab=256k ar=44100 ac=2