Question

为什么我会看到此错误消息：

[Parsed_scale_0 @ 0x559a264c28a0]无效的大小'if（gt（iw'

[AVFilterGraph @ 0x559a268a19e0]初始化过滤器“比例尺”时出错

with args'if（gt（iw'初始化复杂过滤器时出错。

无效的参数

当尝试使用ffmpeg和以下复杂过滤器裁剪视频时：

ffmpeg -f mp4 -ss 01:24 \ 
  -i https://storage.googleapis.com/bucket/video.mp4 \
  -y \
  -filter_complex scale='if(gt(iw,ih),-1,616):if(gt(iw,ih),1440,-1)', crop=1440:616 \
  -an \
  -vcodec libx264 \
  -r 60 -pix_fmt yuv420p \
  -movflags faststart \
  -f mp4 \
  -t 1 \
  /tmp/asset.1554913197962.mp4

如果相关，这是ffprobe的输出：

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'https://storage.googleapis.com/bucket/video.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf57.56.101
  Duration: 00:02:53.76, start: 0.000000, bitrate: 2910 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 2777 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
    "streams": [
        {
            "index": 0,
            "codec_name": "h264",
            "codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
            "profile": "High",
            "codec_type": "video",
            "codec_time_base": "1001/60000",
            "codec_tag_string": "avc1",
            "codec_tag": "0x31637661",
            "width": 1920,
            "height": 1080,
            "coded_width": 1920,
            "coded_height": 1080,
            "has_b_frames": 1,
            "sample_aspect_ratio": "1:1",
            "display_aspect_ratio": "16:9",
            "pix_fmt": "yuv420p",
            "level": 40,
            "color_range": "tv",
            "color_space": "bt709",
            "color_transfer": "bt709",
            "color_primaries": "bt709",
            "chroma_location": "left",
            "refs": 1,
            "is_avc": "true",
            "nal_length_size": "4",
            "r_frame_rate": "30000/1001",
            "avg_frame_rate": "30000/1001",
            "time_base": "1/90000",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 15633630,
            "duration": "173.707000",
            "bit_rate": "2777254",
            "bits_per_raw_sample": "8",
            "nb_frames": "5206",
            "disposition": {
                "default": 1,
                "dub": 0,
                "original": 0,
                "comment": 0,
                "lyrics": 0,
                "karaoke": 0,
                "forced": 0,
                "hearing_impaired": 0,
                "visual_impaired": 0,
                "clean_effects": 0,
                "attached_pic": 0,
                "timed_thumbnails": 0
            },
            "tags": {
                "language": "und",
                "handler_name": "VideoHandler"
            }
        },
        {
            "index": 1,
            "codec_name": "aac",
            "codec_long_name": "AAC (Advanced Audio Coding)",
            "profile": "LC",
            "codec_type": "audio",
            "codec_time_base": "1/44100",
            "codec_tag_string": "mp4a",
            "codec_tag": "0x6134706d",
            "sample_fmt": "fltp",
            "sample_rate": "44100",
            "channels": 2,
            "channel_layout": "stereo",
            "bits_per_sample": 0,
            "r_frame_rate": "0/0",
            "avg_frame_rate": "0/0",
            "time_base": "1/44100",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 7662596,
            "duration": "173.755011",
            "bit_rate": "125588",
            "max_bit_rate": "125588",
            "nb_frames": "7483",
            "disposition": {
                "default": 1,
                "dub": 0,
                "original": 0,
                "comment": 0,
                "lyrics": 0,
                "karaoke": 0,
                "forced": 0,
                "hearing_impaired": 0,
                "visual_impaired": 0,
                "clean_effects": 0,
                "attached_pic": 0,
                "timed_thumbnails": 0
            },
            "tags": {
                "language": "eng",
                "handler_name": "SoundHandler"
            }
        }
    ],
    "format": {
        "filename": "https://storage.googleapis.com/bucket/video.mp4",
        "nb_streams": 2,
        "nb_programs": 0,
        "format_name": "mov,mp4,m4a,3gp,3g2,mj2",
        "format_long_name": "QuickTime / MOV",
        "start_time": "0.000000",
        "duration": "173.755000",
        "size": "63209767",
        "bit_rate": "2910294",
        "probe_score": 100,
        "tags": {
            "major_brand": "isom",
            "minor_version": "512",
            "compatible_brands": "isomiso2avc1mp41",
            "encoder": "Lavf57.56.101"
        }
    }
}

Answer 1

将整个filtergraph用双引号引起来：

"scale='if(gt(iw,ih),-1,616):if(gt(iw,ih),1440,-1)', crop=1440:616"

...或转义逗号：

scale='if(gt(iw\,ih)\,-1\,616):if(gt(iw\,ih)\,1440\,-1)',crop=1440:616

为什么此ffmpeg过滤器会导致“无效尺寸”错误？

1 个答案: