CODEWITHSUNDEEP
c++ffmpeg
TTGroup
TTGroup

Reputation: 3713

Deal with resolution changed while decoding?

I'm using FFMPEG with C++ to read frames and decode them from RTSP Stream on IP Camera.

Anything is ok, but while decoding, I try to change stream resolution config on IP Camera (ex: change from 1280x720 to 1920x1080).

The result is av_read_frame() in while loop still read successful next frames (with new resolution) without error. So I can not detect that change to reinit buffer or reconnect stream to update other stream's information.

av_read_frame() will read an AVPacket, If I can read resolution info in the AVPacket, then I can detect that change and reinit buffer. But I can't see any resolution info in AVPacket struct.

How do I detect a resolution change while reading and decoding the stream?

I'm using many codecs as H264 and H265/H265+. This case happened with all 3 codecs above.

In many cases, I also store the AVPacket for later playback, so there's no need for decode. I need to detect the resolution change immediately to be able to properly build header information to store on the HDD.

Upvotes: 1

Views: 1012

Answers (2)

TTGroup
TTGroup

Reputation: 3713

Use av_parser_parse2() to parse information such as Resolution from AVPacket, and compare it to the old values, to detect the change and then reconnect it again.

Upvotes: 0

szatmary
szatmary

Reputation: 31120

In band resolution changes can not be detected by av_read_frame() because av_read_frame() does not parse the frame, It only reads the data from the stream and places it into a buffer. You will need to use a bitstreram parser, or send the frame to the decoder (if the decoder supports resolution changes). Every codec is different however, so I cant give you more information unless I know what codec you are using.

Upvotes: 2

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