replay: fix video decoding from files with audio streams

[deanlee]

Fixes FrameReader to properly handle video files that contain audio streams.

resolve: #35711

[Copilot]

Pull Request Overview

This PR fixes FrameReader to correctly handle video files that include audio streams by explicitly finding and using the video stream rather than assuming stream 0.

• Use av_find_best_stream to locate the video stream and store its index in video_stream_idx_
• Filter packet reading and decoder acquisition to the identified video stream
• Revise decoding loop to skip non-video packets and return the requested frame

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
tools/replay/framereader.h	Added video_stream_idx_ member to track stream
tools/replay/framereader.cc	Updated stream selection, packet filtering, and decoding logic

Comments suppressed due to low confidence (1)

tools/replay/framereader.cc:83

• Consider adding a test with a sample file containing both audio and video streams to verify that loadFromFile correctly identifies the video stream and processes frames without audio interference.

  video_stream_idx_ = av_find_best_stream(input_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);

[Copilot]

The call to avformat_seek_file uses stream index 0, which may refer to an audio stream if present. Replace the hardcoded 0 with reader->video_stream_idx_ to seek the correct video stream.

Suggested change

	int ret = avformat_seek_file(reader->input_ctx, 0, pos, pos, pos, AVSEEK_FLAG_BYTE);
	int ret = avformat_seek_file(reader->input_ctx, reader->video_stream_idx_, pos, pos, pos, AVSEEK_FLAG_BYTE);

[Copilot]

decodeFrame may return null when the packet does not immediately yield a frame; instead of erroring out here, you should continue reading subsequent packets until the requested frame is decoded.

Suggested change

	rError("Failed to decode frame at index %d", current_idx);
	return false;
	rWarning("Frame not decoded, continuing to read subsequent packets...");
	continue;