Question

目前，我正在根据以下代码检索视频帧：

# Retrieve Images from Videos
for video in list_videos:
    vidcap = cv2.VideoCapture(video)
    success, image = vidcap.read()
    count = 0
    print("Successfully retrieving videos from ", video)
    while success:
        cv2.imwrite('.'+video.split('.')[-2]+'/'+'frame%d.png' %count, image)
        success, image = vidcap.read()
        count += 1
    vidcap.release()

此代码需要大量时间才能从视频中提取帧。有没有更快的方法来实现此代码？

Answer 1

花费最多时间的代码行是：

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp2.2</TargetFramework>
    <UserSecretsId>aspnet-xxx</UserSecretsId>
    <ApplicationInsightsResourceId>/subscriptions/xxx/resourcegroups/xxx/providers/microsoft.insights/components/xxx</ApplicationInsightsResourceId>
    <ApplicationInsightsAnnotationResourceId>/subscriptions/xxx/resourcegroups/MyIndigoHealth/providers/microsoft.insights/components/xxx</ApplicationInsightsAnnotationResourceId>
    <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
    <TypeScriptToolsVersion>3.1</TypeScriptToolsVersion>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.6.1" />
    <PackageReference Include="Microsoft.AspNetCore.App" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.2.3" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="2.2.3">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
    </PackageReference>
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="2.2.3" PrivateAssets="All" />
    <PackageReference Include="Neleus.DependencyInjection.Extensions" Version="1.0.0" />
  </ItemGroup>

  <ItemGroup>
    <Folder Include="Areas\Identity\Services\" />
  </ItemGroup>

  <ItemGroup>
    <WCFMetadata Include="Connected Services" />
  </ItemGroup>

</Project>

使该行更快的一种方法是在将其写入硬盘之前调整图像的大小（使其更小）：

cv2.imwrite('.'+video.split('.')[-2]+'/'+'frame%d.png' %count, image)

另一种更快处理视频的方法是将图像写入内存，而不是硬盘。仅当您有足够的RAM来容纳图像时，此方法才有效。这可能会导致灾难性的计算机崩溃：

cv2.resize(image, (640,480))

如何更快地从视频中提取帧？

1 个答案: