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--- ffmpeg:video:duration [2025/05/27 18:08] – created peter
+++ ffmpeg:video:duration [2025/05/27 18:34] (current) – [By Packet duration_time] peter
@@ Line 1: / Line 1: @@
 ====== ffmpeg - Video - Duration ======
+===== Using Regex =====
 <code bash>
@@ Line 20: / Line 22: @@
 <WRAP info>
-**NOTE:**  This returns an estimate of the duration based on the bitrate and size of the file.
+**NOTE:**  This gets the figures directly from ffmpeg.
+  * This returns an estimate of the duration based on the bitrate and size of the file.
+</WRAP>
+----
+===== Getting the data from the video stream =====
+<code bash>
+ffprobe -v error -select_streams v:0 -show_entries stream=duration -of default=noprint_wrappers=1:nokey=1 "input.mkv"
+</code>
+<WRAP info>
+**NOTE:**  This often returns N/A for .mkv files.
+</WRAP>
+----
+===== Getting the data from the container =====
+<code bash>
+ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "input.mkv"
+ffprobe -v error -select_streams v:0 -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "input.mkv"
+</code>
+<WRAP important>
+**WARNING:**  This returns the duration of the entire container, and not just the duration of the video.
+</WRAP>
+----
+===== By Packet duration_time =====
+This method reads each video packet, individually, and totals up each packet size.
+  * Sums up the **duration_time** of the **-show_entries** command.
+<code bash>
+video_pkt_durations=$(ffprobe -v error -select_streams v:0 -skip_frame nokey -show_entries packet=duration_time -of default=nokey=1:noprint_wrappers=1 "input.mkv")
+sum_video_pkt_duration=0
+precision=6
+count_video_pkt_duration=0
+#echo "Calculating video pkt_duration..."
+for video_pkt_duration in $video_pkt_durations; do
+  sum_video_pkt_duration=$(echo "${sum_video_pkt_duration} + ${video_pkt_duration}" | bc)
+  (( count_video_pkt_duration++ ))
+done;
+video_duration=$( echo "scale=${precision}; ${sum_video_pkt_duration} " | bc)
+echo "DURATION=${video_duration}"
+echo "VIDEO FRAMES=${count_video_pkt_duration}"
+</code>
+<WRAP info>
+**NOTE:**  This is very accurate but may take a while.
+</WRAP>
+----
+===== Calculate duration using Size and Bitrate =====
+<code bash>
+duration=$( echo "scale=6; (${video_size} * 8) / ${bitrate}" | bc)
+</code>
+----
+===== Calculate duration using Size and Bitrate =====
+<code bash>
+duration = NUMBER_OF_FRAMES / FPS
+</code>
+<WRAP info>
+**NOTE:**  Returns the duration in seconds.
 </WRAP>