AVDurationEstimationMethod 1561 libavformat/avformat.h     enum AVDurationEstimationMethod duration_estimation_method;
AVDurationEstimationMethod 1755 libavformat/avformat.h enum AVDurationEstimationMethod av_fmt_ctx_get_duration_estimation_method(const AVFormatContext* ctx);
AVDurationEstimationMethod  124 libavformat/options.c enum AVDurationEstimationMethod av_fmt_ctx_get_duration_estimation_method(const AVFormatContext* ctx)