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--- doc:appunti:linux:video:ffmpeg_final_rendering [2024/07/31 08:18] – [Pixel format considerations] niccolo
+++ doc:appunti:linux:video:ffmpeg_final_rendering [2024/07/31 09:57] (current) – [Two pass encoding] niccolo
@@ Line 1: / Line 1: @@
-====== Final Rendering in x264 with ffmpeg ======
+====== Final Rendering with libx264 and ffmpeg ======
 Whether you are working with **Ffmepg**, **Avidemux** or **Olive Video Editor**, you should be wondering what parameters to use to final render a video montage. Here are my choices for some specific purpose.
 ===== Encoding for High Definition Video =====
@@ Line 42: / Line 41: @@
 Notice that we selected a target bitrate of **4 Mbps** and a maximum bitrate of **6 Mbps**. Sepcifying both the //bitrate// and the //max bitrate tolerance// requires also to specify a //buffer size//; ''ffmpeg'' will re-adjust the bitrate on each buffer size, so if the buffer size is equal to the max rate, ffmpeg will re-calculate the bitrate at least every second.
-=====  Two pass encoding =====
 =====  A warning about the H.264 profile level =====
@@ Line 57: / Line 54: @@
 | High@5          | 1920x1080    |    4 | No   |
 | High@5          | 1920x1080    |    6 | No   |
+=====  Two pass encoding =====
+Here it is a recipe of **two-pass encoding** from an high quality //master// produced with [[olive_editor_tools#export_media|Olive Video Editor]]. The target video will be a **6 Mbit** stream, **1920x1080@30**. The profile level selected is **High@L4.1**, so that the video will play nicely with Kodi 19.4 on the Raspberry Pi 4:
+<code bash>
+TITLE='Marocco - Maggio 2024'
+ffmpeg \
+    -i full32bit-veryslow-crf18-fullcolor.mkv \
+    -metadata title="$TITLE" -metadata:s:v:0 title="$TITLE" \
+    -vcodec 'libx264' -pix_fmt 'yuvj420p' -preset 'veryslow' -tune 'film' \
+    -profile:v 'high' -level:v 4.1 \
+    -b:v 6M -maxrate:v 9M -bufsize:v 18M \
+    -x264-params 'keyint=64' \
+    -an \
+    -pass 1 \
+    -f matroska -y /dev/null
+# First pass produces two files: ffmpeg2pass-0.log and ffmpeg2pass-0.log.mbtree.
+ffmpeg \
+    -i full32bit-veryslow-crf18-fullcolor.mkv \
+    -metadata title="$TITLE" -metadata:s:v:0 title="$TITLE" \
+    -vcodec 'libx264' -pix_fmt 'yuvj420p' -preset 'veryslow' -tune 'film' \
+    -profile:v 'high' -level:v 4.1 \
+    -b:v 6M -maxrate:v 9M -bufsize:v 18M \
+    -x264-params 'keyint=64' \
+    -an \
+    -pass 2 \
+    -f matroska marocco-twopass-6max9-level41.mkv
+</code>
+The transcoding works on the video only, suppressing any audio stream (**%%-an%%** option). Using the **keyint=64** option will produce a keyframe every 64 frames (about two seconds), this make seeking back and forward in the video more smooth.
 =====  Pixel format considerations =====