使用FFmpeg搭配HDMI转USB采集卡录制1280x1024视频时画面拉伸、比例异常的解决求助

阿华AIGC实验室

2026-4-22

我现在在Windows环境下，想用FFmpeg配合HDMI转USB采集卡录制另一台PC的屏幕。已经把目标PC的屏幕复制到采集卡创建的第二个虚拟显示器上，这个显示器的分辨率是1280x1024，而且采集卡本身是支持这个分辨率的——我用下面的命令验证过：

C:\ffmpeg>ffmpeg.exe -hide_banner -f dshow -list_options true -i video="MyVideoDeviceName" 2>&1 | findstr "mjpeg.*1280x1024"

返回结果显示：

[dshow @ 0000017d0f699e40] vcodec=mjpeg min s=1280x1024 fps=10 max s=1280x1024 fps=60.0002
[dshow @ 0000017d0f699e40] vcodec=mjpeg min s=1280x1024 fps=10 max s=1280x1024 fps=60.0002

接下来，我尝试用这条命令录制全屏显示的图片：

C:\ffmpeg>ffmpeg.exe -hide_banner -y -f dshow -rtbufsize 100M -video_size 1280x1024 -framerate 30 -vcodec mjpeg -i video="MyVideoDeviceName":audio="MyAudioDeviceName" -vcodec libx264 -b:v 7000k -acodec aac test.mp4

执行时的输出信息看起来都正常：

Guessed Channel Layout for Input Stream #0.1 : stereo
Input #0, dshow, from 'video=MyVideoDeviceName:audio=MyAudioDeviceName':
Duration: N/A, start: 1533.874000, bitrate: N/A
Stream #0:0: Video: mjpeg (Baseline) (MJPG / 0x47504A4D), yuvj422p(pc, bt470bg/unknown/unknown), 1280x1024, 30 fps, 30 tbr, 10000k tbn, 10000k tbc
Stream #0:1: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (mjpeg (native) -> h264 (libx264))
Stream #0:1 -> #0:1 (pcm_s16le (native) -> aac (native))
Press [q] to stop, [?] for help
Output #0, mp4, to 'test.mp4':
Metadata:
encoder : Lavf58.31.104
Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuvj422p(pc, progressive), 1280x1024, q=-1--1, 7000 kb/s, 30 fps, 10000k tbn, 30 tbc
Metadata:
encoder : Lavc58.55.101 libx264
Side data:
cpb: bitrate max/min/avg: 0/0/7000000 buffer size: 0 vbv_delay: 18446744073709551615
Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s
Metadata:
encoder : Lavc58.55.101 aac
frame= 74 fps= 34 q=-1.0 Lsize= 1247kB time=00:00:02.36 bitrate=4318.0kbits/s dup=4 drop=0 speed= 1.1x

用MediaInfo查看生成的test.mp4文件信息，各项参数也都符合预期：

General
Complete name : test.mp4
Format : MPEG-4
Format profile : Base Media
Codec ID : isom (isom/iso2/avc1/mp41)
File size : 1.22 MiB
Duration : 2 s 467 ms
Overall bit rate mode : Variable
Overall bit rate : 4 142 kb/s
Writing application : Lavf58.31.104
Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High 4:2:2@L3.2
Format settings : CABAC / 4 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 4 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 2 s 467 ms
Bit rate : 4 029 kb/s
Nominal bit rate : 7 000 kb/s
Width : 1 280 pixels
Height : 1 024 pixels
Display aspect ratio : 5:4
Frame rate mode : Constant
Frame rate : 30.000 FPS
Color space : YUV
Chroma subsampling : 4:2:2
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.102
Stream size : 1.18 MiB (97%)
Writing library : x264 core 158 r2984 3759fcb
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=30 / lookahead_threads=5 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=abr / mbtree=1 / bitrate=7000 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Color range : Full
Codec configuration box : avcC
Audio
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 2 s 43 ms
Bit rate mode : Variable
Bit rate : 123 kb/s
Maximum bit rate : 128 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 44.1 kHz
Frame rate : 43.066 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 30.7 KiB (2%)
Default : Yes
Alternate group : 1