Commit 7b95d353fa for ffmpeg

commit 7b95d353fa1c548ec65c9fd3e3908cc6c5a4e403
Author: Michael Niedermayer <michael@niedermayer.cc>
Date:   Wed Oct 7 00:05:29 2026 +0200

    avformat/wavenc: Keep the peak envelope channel index across packets

    The channel index restarted at 0 for every packet, so after a packet
    that ended inside a sample frame the following samples were counted
    for the wrong channels.

    Wrong peak values Replicated through UnModified FFmpeg
    Found during triage of the security report LHiad3FmdAmI

diff --git a/libavformat/wavenc.c b/libavformat/wavenc.c
index 9de3f7b789..9566850503 100644
--- a/libavformat/wavenc.c
+++ b/libavformat/wavenc.c
@@ -86,6 +86,7 @@ typedef struct WAVMuxContext {
     int peak_block_size;
     int peak_format;
     int peak_block_pos;
+    int peak_channel;
     int peak_ppv;
     int peak_bps;
 } WAVMuxContext;
@@ -404,7 +405,7 @@ static int wav_write_packet(AVFormatContext *s, AVPacket *pkt)
         avio_write(pb, pkt->data, pkt->size);

     if (wav->write_peak) {
-        int c = 0;
+        int c = wav->peak_channel;
         int i;
         for (i = 0; i < pkt->size; i += wav->peak_bps) {
             if (wav->peak_bps == 1) {
@@ -424,6 +425,7 @@ static int wav_write_packet(AVFormatContext *s, AVPacket *pkt)
                 }
             }
         }
+        wav->peak_channel = c;
     }

     if(pkt->pts != AV_NOPTS_VALUE) {