Ytdyklly

If I do have multiple URL links for videos or audios, how can I determine which one has the best quality. Is there a header information, which tells me about the quality of the video - even the content type is different?

Example for Videos:

• The content-type of the first URL is: video/3gpp
  


• The content-type of the second URL is: video/mp4
  

Example for Audios:

• The content-type of the first URL is: audio/3gpp
  


• The content-type of the second URL is: audio/webm
  

Is it possible to compare them based on quality - which I get from the header information? Im asking this for URLs with only Audio and URLs with only Video (audio and video).

The HTTP headers are unlikely to tell you anything more than the video or audio container format. But most modern video and audio container formats can have any number of different qualities of video or audio stored inside them. To know what quality the actual data inside the container file is, you'll have to begin downloading the file and look at the internal headers of the file (not the HTTP headers).

That said, since your example includes 3GPP HTTP content-types, I would guess that those are lower-quality than the MPEG-4 and WebM versions, because 3GPP video was originally designed as low-bitrate video that could easily stream across slow (by today's standards) early 3G networks to flip phones with tiny low-res screens from like 2006.

This answer is just extension of Spiff's answer with real examples.

For example, here I choose this video Running your First Docker Container in Azure from Channel9 MSDN. It has four file formats of that video. What I did? Answer: Use curl --head to show ONLY header of that HTTP/GET request which contains the Content-Type and Content-Length. Then download those. Use ffmpeg -i to show the downloaded video file encoding information (only important sections are provided below). Here are the three of them:

1. Low quality MP4:

$> curl --head "https://sec.ch9.ms/ch9/7a84/8269395e-c022-4672-8b43-3cf1b5d57a84/jay-gordon-docker-in-azure.mp4"

Content-Length: 42,102,244

Content-Type: video/mp4



$> ffmpeg -i jay-gordon-docker-in-azure.mp4

Duration: 00:17:54.05, start: 0.000000, bitrate: 313 kb/s

Stream #0:0(eng): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 640x360, 210 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)

Metadata:

  handler_name    : ?Mainconcept Video Media Handler

Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 96 kb/s (default)

Metadata:

  handler_name    : #Mainconcept MP4 Sound Media Handler

2. Mid Quality MP4:

$> curl --head "https://sec.ch9.ms/ch9/7a84/8269395e-c022-4672-8b43-3cf1b5d57a84/jay-gordon-docker-in-azure_mid.mp4"

Content-Length: 129,621,802

Content-Type: video/mp4



$> ffmpeg -i jay-gordon-docker-in-azure_mid.mp4

Duration: 00:17:54.05, start: 0.000000, bitrate: 965 kb/s

Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720, 828 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)

Metadata:

  handler_name    : ?Mainconcept Video Media Handler

Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s (default)

Metadata:

  handler_name    : #Mainconcept MP4 Sound Media Handler

3. High Quality MP4:

$> curl --head "https://sec.ch9.ms/ch9/7a84/8269395e-c022-4672-8b43-3cf1b5d57a84/jay-gordon-docker-in-azure_high.mp4"

Content-Length: 385,374,160

Content-Type: video/mp4



$> ffmpeg -i jay-gordon-docker-in-azure_high.mp4

Duration: 00:17:54.05, start: 0.000000, bitrate: 2870 kb/s

Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 2701 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)

Metadata:

  handler_name    : ?Mainconcept Video Media Handler

Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 160 kb/s (default)

Metadata:

  handler_name    : #Mainconcept MP4 Sound Media Handler

Compare these three command output. As the quality increase Content-Length increase thus bitrate of audio and video. So, it may be possible to speculate the video quality from Content-Length in curl --head command but HTTP header does not provide full video encoding. To know more about the video encoding, one has to download the file. Only URL can not provide those information.

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  Used tools:

  
  
  
  
  
  • curl
  
  
  • aria2
  
  
  • ffmpeg