I'm producing MPEGTS streams (h264/aac) using ffmpeg, so I know exactly how
they are coded, and I could modify that if needed.
Now, when I receive them in my own code, I always have to run them through
avformat_open_input and avformat_find_stream_info to get the settings into the
codec context.
Because udp mpegts streams have no header, both avformat_open_input and
avformat_find_stream_info sometimes have problems to get all settings
correctly.
However, all settings are known, and so I try to inform avformat_open_input and
avformat_find_stream_info about them, using a AVDictionary.
However, despite setting the video_size to 720x576, I often get "unspecified
size". Other AVDictionary options such as "probesize" are honored though.
Ideally I want to skip the avformat_find_stream_info step completely and preset
all settings. But how to do that correctly?
Also sometimes avformat_open_input does not get it correctly that there is a
video and an audio stream.
I'm reading the stream though a memory buffer, and not directly from a file or
url. This is what I tried:
======
av_dict_set(&format_opts, "video_size", "720x576", 0); <<== seems to be
ignored
// av_dict_set(&format_opts, "pixel_format",
av_get_pix_fmt_name(ffmpeg::PIX_FMT_YUV420P), 0);
av_dict_set(&format_opts, "pixel_format", "yuv420p", 0);
av_dict_set(&format_opts, "sample_format", "fltp", 0);
av_dict_set(&format_opts, "analyzeduration", "8000000", 0); <<== honored
av_dict_set(&format_opts, "probesize", "8000000", 0); <<== honored
av_dict_set(&format_opts, "channels", "2", 0);
av_dict_set(&format_opts, "sample_rate", "48000", 0);
av_dict_set(&format_opts, "seekable", "0", 0);
...
err = avformat_open_input(&pFormatCtx, "", inputFmt, &format_opts);
=> sometimes sees one stream only
av_dict_set(&format_opts, "video_size", "720x576", 0); <<== seems to be
ignored
...
err = avformat_find_stream_info(pFormatCtx, &format_opts);
av_dump_format(pFormatCtx, 0, "Memory Buffer", false);
=> often says "unspecified size"
======
I'm using the very latest ffmpeg 1.0.3 from 2 days ago.
My Questions are:
How do I pass the video size to avformat_open_input and
avformat_find_stream_info so that it is taken?
Which settings do i have to set to set (and how) to avoid the need for
avformat_find_stream_info?
How do i tell avformat_open_input that there is a video stream and an audio
stream, or help it to find them (possible a change in the encoding parameters)?
Thanks for any hints or help!
Regards,
Kalileo
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