Commit ce1f4c78d1 for ffmpeg

commit ce1f4c78d1c3642049a01f9d8f24263cc1782fcd
Author: Michael Niedermayer <michael@niedermayer.cc>
Date:   Thu Sep 24 00:16:33 2026 +0200

    avformat: document that muxers require padded packet data

    Muxers read packet data the same way decoders do, with reads that may
    extend a few bytes past the end of the data, so a packet handed to
    av_write_frame() or av_interleaved_write_frame() needs the same
    AV_INPUT_BUFFER_PADDING_SIZE bytes after it that decoder input needs.
    Packets from libavcodec and from demuxers have them.

    Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index d8c1478b5f..07ed2764cd 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -2710,6 +2710,10 @@ int avformat_init_output(AVFormatContext *s, AVDictionary **options);
  *            set to the index of the corresponding stream in @ref
  *            AVFormatContext.streams "s->streams".
  *            <br>
+ *            The packet data must be followed by AV_INPUT_BUFFER_PADDING_SIZE
+ *            bytes, as for decoder input; packets from libavcodec and from
+ *            demuxers are.
+ *            <br>
  *            The timestamps (@ref AVPacket.pts "pts", @ref AVPacket.dts "dts")
  *            must be set to correct values in the stream's timebase (unless the
  *            output format is flagged with the AVFMT_NOTIMESTAMPS flag, then
@@ -2754,6 +2758,10 @@ int av_write_frame(AVFormatContext *s, AVPacket *pkt);
  *            set to the index of the corresponding stream in @ref
  *            AVFormatContext.streams "s->streams".
  *            <br>
+ *            The packet data must be followed by AV_INPUT_BUFFER_PADDING_SIZE
+ *            bytes, as for decoder input; packets from libavcodec and from
+ *            demuxers are.
+ *            <br>
  *            The timestamps (@ref AVPacket.pts "pts", @ref AVPacket.dts "dts")
  *            must be set to correct values in the stream's timebase (unless the
  *            output format is flagged with the AVFMT_NOTIMESTAMPS flag, then