From e19d48dfce52f1417f7f06143b96fed00cbcdc52 Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Mon, 26 May 2014 22:14:14 +0200
Subject: [PATCH] flac muxer: support reading updated extradata from side data

---
 libavformat/flacenc.c        | 37 ++++++++++++++++++++++++++++--------
 libavformat/flacenc.h        |  4 ++--
 libavformat/flacenc_header.c |  8 ++++----
 libavformat/matroskaenc.c    |  3 ++-
 4 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/libavformat/flacenc.c b/libavformat/flacenc.c
index 0365764605..a686826543 100644
--- a/libavformat/flacenc.c
+++ b/libavformat/flacenc.c
@@ -31,6 +31,9 @@
 typedef struct FlacMuxerContext {
     const AVClass *class;
     int write_header;
+
+    /* updated streaminfo sent by the encoder at the end */
+    uint8_t *streaminfo;
 } FlacMuxerContext;
 
 static int flac_write_block_padding(AVIOContext *pb, unsigned int n_padding_bytes,
@@ -80,7 +83,8 @@ static int flac_write_header(struct AVFormatContext *s)
     if (!c->write_header)
         return 0;
 
-    ret = ff_flac_write_header(s->pb, codec, 0);
+    ret = ff_flac_write_header(s->pb, codec->extradata,
+                               codec->extradata_size, 0);
     if (ret)
         return ret;
 
@@ -118,17 +122,14 @@ static int flac_write_header(struct AVFormatContext *s)
 static int flac_write_trailer(struct AVFormatContext *s)
 {
     AVIOContext *pb = s->pb;
-    uint8_t *streaminfo;
-    enum FLACExtradataFormat format;
     int64_t file_size;
     FlacMuxerContext *c = s->priv_data;
+    uint8_t *streaminfo = c->streaminfo ? c->streaminfo :
+                                          s->streams[0]->codec->extradata;
 
-    if (!c->write_header)
+    if (!c->write_header || !streaminfo)
         return 0;
 
-    if (!avpriv_flac_is_extradata_valid(s->streams[0]->codec, &format, &streaminfo))
-        return -1;
-
     if (pb->seekable) {
         /* rewrite the STREAMINFO header block data */
         file_size = avio_tell(pb);
@@ -139,12 +140,32 @@ static int flac_write_trailer(struct AVFormatContext *s)
     } else {
         av_log(s, AV_LOG_WARNING, "unable to rewrite FLAC header.\n");
     }
+
+    av_freep(&c->streaminfo);
+
     return 0;
 }
 
 static int flac_write_packet(struct AVFormatContext *s, AVPacket *pkt)
 {
-    avio_write(s->pb, pkt->data, pkt->size);
+    FlacMuxerContext *c = s->priv_data;
+    uint8_t *streaminfo;
+    int streaminfo_size;
+
+    /* check for updated streaminfo */
+    streaminfo = av_packet_get_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA,
+                                         &streaminfo_size);
+    if (streaminfo && streaminfo_size == FLAC_STREAMINFO_SIZE) {
+        av_freep(&c->streaminfo);
+
+        c->streaminfo = av_malloc(FLAC_STREAMINFO_SIZE);
+        if (!c->streaminfo)
+            return AVERROR(ENOMEM);
+        memcpy(c->streaminfo, streaminfo, FLAC_STREAMINFO_SIZE);
+    }
+
+    if (pkt->size)
+        avio_write(s->pb, pkt->data, pkt->size);
     return 0;
 }
 
diff --git a/libavformat/flacenc.h b/libavformat/flacenc.h
index 3964ce45e1..54dd8333bc 100644
--- a/libavformat/flacenc.h
+++ b/libavformat/flacenc.h
@@ -26,8 +26,8 @@
 #include "libavcodec/bytestream.h"
 #include "avformat.h"
 
-int ff_flac_write_header(AVIOContext *pb, AVCodecContext *codec,
-                         int last_block);
+int ff_flac_write_header(AVIOContext *pb, uint8_t *extradata,
+                         int extradata_size, int last_block);
 
 int ff_flac_is_native_layout(uint64_t channel_layout);
 
diff --git a/libavformat/flacenc_header.c b/libavformat/flacenc_header.c
index a6e2b59f54..4f9bb206e5 100644
--- a/libavformat/flacenc_header.c
+++ b/libavformat/flacenc_header.c
@@ -26,8 +26,8 @@
 #include "avformat.h"
 #include "flacenc.h"
 
-int ff_flac_write_header(AVIOContext *pb, AVCodecContext *codec,
-                         int last_block)
+int ff_flac_write_header(AVIOContext *pb, uint8_t *extradata,
+                         int extradata_size, int last_block)
 {
     uint8_t header[8] = {
         0x66, 0x4C, 0x61, 0x43, 0x00, 0x00, 0x00, 0x22
@@ -35,14 +35,14 @@ int ff_flac_write_header(AVIOContext *pb, AVCodecContext *codec,
 
     header[4] = last_block ? 0x80 : 0x00;
 
-    if (codec->extradata_size < FLAC_STREAMINFO_SIZE)
+    if (extradata_size < FLAC_STREAMINFO_SIZE)
         return AVERROR_INVALIDDATA;
 
     /* write "fLaC" stream marker and first metadata block header */
     avio_write(pb, header, 8);
 
     /* write STREAMINFO */
-    avio_write(pb, codec->extradata, FLAC_STREAMINFO_SIZE);
+    avio_write(pb, extradata, FLAC_STREAMINFO_SIZE);
 
     return 0;
 }
diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 919cdfd722..7d3050eaeb 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -477,7 +477,8 @@ static int put_flac_codecpriv(AVFormatContext *s,
     int write_comment = (codec->channel_layout &&
                          !(codec->channel_layout & ~0x3ffffULL) &&
                          !ff_flac_is_native_layout(codec->channel_layout));
-    int ret = ff_flac_write_header(pb, codec, !write_comment);
+    int ret = ff_flac_write_header(pb, codec->extradata, codec->extradata_size,
+                                   !write_comment);
 
     if (ret < 0)
         return ret;