关于Seedance 2.0 Fast「预览视频」与「官方下载」两个文件大小差别很大的情况

[catscarlet]

根据目前（2026-03-22）的情况来看，Seedance 2.0 Fast「预览视频」下载下来的视频文件，与「官方下载」提供的视频文件，文件大小差别很大。

目前的状况是：

• 分辨率：预览视频和官方下载都是720p的（16:9和9:16），分辨率是相同的。其他视频比例基本一样。
• 帧率：也是相同的24fps。预览视频是固定24fps；官方下载是动态帧率，但是平均帧率约是24fps。
• 码率：码率不同 。Seedance 2.0 Fast预览视频现在码率很低，平均在1Mbps到2Mbps左右，最大4Mbps。官方下载码率则是6Mbps多。视频3.0Fast和以前的模型，预览和下载的码率是基本相同的。

算是官方的封杀手段吧。凑合用吧，反正也不是没有办法，都是自己动动脑筋和手指就可以解决的问题。

付费用户又不遭这个罪。
本项目究其目的，还是针对免费用户做休闲娱乐使用。

[catscarlet]

以下提供 Seedance 2.0 Fast 的「预览视频」与「官方下载」的MediaInfo来展示两个文件的区别：

Seedance 2.0 Fast 预览视频文件

General
Complete name                            : /home/cat/Download/预览视频.mp4
Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom (isom/iso2/avc1/mp41)
File size                                : 3.03 MiB
Duration                                 : 15 s 70 ms
Overall bit rate                         : 1 689 kb/s
Frame rate                               : 24.000 FPS
comment                                  : vid:v02870g10004d6jkjkfog65uf94ik490
encoder                                  : Lavf58.76.100

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L3.1
Format settings                          : CABAC / 5 Ref Frames
Format settings, CABAC                   : Yes
Format settings, Reference frames        : 5 frames
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 15 s 42 ms
Bit rate                                 : 1 556 kb/s
Maximum bit rate                         : 4 000 kb/s
Width                                    : 1 280 pixels
Height                                   : 720 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 24.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.070
Stream size                              : 2.79 MiB (92%)
Codec configuration box                  : avcC

Audio
ID                                       : 2
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : mp4a-40-2
Duration                                 : 15 s 70 ms
Source duration                          : 15 s 116 ms
Bit rate mode                            : Constant
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                              : 236 KiB (8%)
Source stream size                       : 237 KiB (8%)
Default                                  : Yes
Alternate group                          : 1
mdhd_Duration                            : 15070

Seedance 2.0 Fast 官方下载视频文件

General
Complete name                            : /home/cat/Download/jimeng-2026-03-03-8500.mp4
Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom (isom/iso2/avc1/mp41)
File size                                : 11.6 MiB
Duration                                 : 15 s 70 ms
Overall bit rate                         : 6 441 kb/s
Frame rate                               : 24.040 FPS
major_brand                              : isom
minor_version                            : 512
compatible_brands                        : isomiso2avc1mp41
comment                                  : vid:v02870g10004d6jkjkfog65uf94ik490
LvMetaInfo                               : {"data":{"os":"","product":"dreamina","exportType":"generation","videoId":"0"}}
UserComment                              : {"aigc_label_type":0,"source_info":"dreamina"}
com.apple.quicktime.artwork              : {"data":{"os":"","product":"dreamina","exportType":"generation","videoId":"0"}}
AIGC                                     : {"Label": "1", "ContentProducer": "00119144030008867405X210001", "ProduceID": "v02870g10004d6jkjkfog65uf94ik490", "ContentPropagator": "00119144030008867405X220001", "PropagateID": "v02870g10004d6jkjkfog65uf94ik490"}
encoder                                  : Lavf58.76.100

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@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                                 : 15 s 17 ms
Bit rate                                 : 6 325 kb/s
Width                                    : 1 280 pixels
Height                                   : 720 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Variable
Frame rate                               : 24.040 FPS
Minimum frame rate                       : 20.000 FPS
Maximum frame rate                       : 60.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.285
Stream size                              : 11.3 MiB (98%)
Writing library                          : bvc0ot v2.2.1.3-20250220
Codec configuration box                  : avcC

Audio
ID                                       : 2
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : mp4a-40-2
Duration                                 : 15 s 70 ms
Source duration                          : 15 s 116 ms
Bit rate mode                            : Constant
Bit rate                                 : 129 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                              : 236 KiB (2%)
Source stream size                       : 237 KiB (2%)
Default                                  : Yes
Alternate group                          : 1
mdhd_Duration                            : 15070

「预览视频」与「官方下载」在码率部分相差很大。

[catscarlet]

以下提供 视频 3.0 Fast 的「预览视频」与「官方下载」的MediaInfo来展示两个文件的区别：

视频 3.0 Fast 预览视频文件

General
Complete name                            : /home/cat/Download/视频 3.0 Fast 预览视频.mp4
Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom (isom/iso2/avc1/mp41)
File size                                : 9.32 MiB
Duration                                 : 12 s 184 ms
Overall bit rate                         : 6 415 kb/s
Frame rate                               : 24.049 FPS
LvMetaInfo                               : {"data":{"os":"","product":"dreamina","exportType":"generation","videoId":"0"}}
UserComment                              : {"aigc_label_type":0,"source_info":"dreamina"}
com.apple.quicktime.artwork              : {"data":{"os":"","product":"dreamina","exportType":"generation","videoId":"0"}}
comment                                  : vid:v02870g10004d6jfq3nog65mv0d7dhvg
encoder                                  : Lavf58.76.100

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L4
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                                 : 12 s 184 ms
Bit rate                                 : 6 411 kb/s
Width                                    : 832 pixels
Height                                   : 1 120 pixels
Display aspect ratio                     : 0.743
Frame rate mode                          : Variable
Frame rate                               : 24.049 FPS
Minimum frame rate                       : 20.000 FPS
Maximum frame rate                       : 60.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.286
Stream size                              : 9.31 MiB (100%)
Writing library                          : bvc0ot v2.2.1.3-20250220
Codec configuration box                  : avcC

视频 3.0 Fast 官方下载视频文件

General
Complete name                            : /home/cat/Download/jimeng-2026-03-03-3330.mp4
Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom (isom/iso2/avc1/mp41)
File size                                : 9.32 MiB
Duration                                 : 12 s 184 ms
Overall bit rate                         : 6 416 kb/s
Frame rate                               : 24.049 FPS
major_brand                              : isom
minor_version                            : 512
compatible_brands                        : isomiso2avc1mp41
comment                                  : vid:v02870g10004d6jfq3nog65mv0d7dhvg
LvMetaInfo                               : {"data":{"os":"","product":"dreamina","exportType":"generation","videoId":"0"}}
UserComment                              : {"aigc_label_type":0,"source_info":"dreamina"}
com.apple.quicktime.artwork              : {"data":{"os":"","product":"dreamina","exportType":"generation","videoId":"0"}}
AIGC                                     : {"Label": "1", "ContentProducer": "00119144030008867405X210001", "ProduceID": "v02870g10004d6jfq3nog65mv0d7dhvg", "ContentPropagator": "00119144030008867405X220001", "PropagateID": "v02870g10004d6jfq3nog65mv0d7dhvg"}
encoder                                  : Lavf58.76.100

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L4
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                                 : 12 s 184 ms
Bit rate                                 : 6 411 kb/s
Width                                    : 832 pixels
Height                                   : 1 120 pixels
Display aspect ratio                     : 0.743
Frame rate mode                          : Variable
Frame rate                               : 24.049 FPS
Minimum frame rate                       : 20.000 FPS
Maximum frame rate                       : 60.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.286
Stream size                              : 9.31 MiB (100%)
Writing library                          : bvc0ot v2.2.1.3-20250220
Codec configuration box                  : avcC

视频 3.0 Fast 的预览视频和官方下载，在Video部分是基本相同。