Re: [FFmpeg-devel] [PATCH] ffmpeg: copy the extradata from encoder to muxer

[Andreas Cadhalpun]

On 27.10.2016 21:37, James Almer wrote:
> If apng encoder needs to add new extradata in a packet, it should do it
> with av_packet_new_side_data() instead.

Thanks for the hint. Attached is a patch fixing it that way.

Best regards,
Andreas


>From 4325ccdaf3bb7c74312cbaeb49d76fe535f18956 Mon Sep 17 00:00:00 2001
From: Andreas Cadhalpun <andreas.cadhal...@googlemail.com>
Date: Thu, 27 Oct 2016 22:34:48 +0200
Subject: [PATCH] apng: use side data to pass extradata to muxer

This fixes creating apng files, which is broken since commit
5ef19590802f000299e418143fc2301e3f43affe.

Signed-off-by: Andreas Cadhalpun <andreas.cadhal...@googlemail.com>
---
 libavcodec/pngenc.c   |  4 ++++
 libavformat/apngenc.c | 27 ++++++++++++++++++++++++---
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/libavcodec/pngenc.c b/libavcodec/pngenc.c
index 00c830e..1a308f2 100644
--- a/libavcodec/pngenc.c
+++ b/libavcodec/pngenc.c
@@ -917,6 +917,10 @@ static int encode_apng(AVCodecContext *avctx, AVPacket *pkt,
     if (s->last_frame) {
         uint8_t* last_fctl_chunk_start = pkt->data;
         uint8_t buf[26];
+        uint8_t *side_data = av_packet_new_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA, avctx->extradata_size);
+        if (!side_data)
+            return AVERROR(ENOMEM);
+        memcpy(side_data, avctx->extradata, avctx->extradata_size);
 
         AV_WB32(buf + 0, s->last_frame_fctl.sequence_number);
         AV_WB32(buf + 4, s->last_frame_fctl.width);
diff --git a/libavformat/apngenc.c b/libavformat/apngenc.c
index e25df2e..f702667 100644
--- a/libavformat/apngenc.c
+++ b/libavformat/apngenc.c
@@ -101,15 +101,29 @@ static int apng_write_header(AVFormatContext *format_context)
     return 0;
 }
 
-static void flush_packet(AVFormatContext *format_context, AVPacket *packet)
+static int flush_packet(AVFormatContext *format_context, AVPacket *packet)
 {
     APNGMuxContext *apng = format_context->priv_data;
     AVIOContext *io_context = format_context->pb;
     AVStream *codec_stream = format_context->streams[0];
     AVCodecParameters *codec_par = codec_stream->codecpar;
+    uint8_t *side_data = NULL;
+    int side_data_size = 0;
 
     av_assert0(apng->prev_packet);
 
+    if (packet)
+        side_data = av_packet_get_side_data(packet, AV_PKT_DATA_NEW_EXTRADATA, &side_data_size);
+
+    if (side_data_size) {
+        av_freep(&codec_par->extradata);
+        codec_par->extradata = av_mallocz(side_data_size + AV_INPUT_BUFFER_PADDING_SIZE);
+        if (!codec_par->extradata)
+            return AVERROR(ENOMEM);
+        codec_par->extradata_size = side_data_size;
+        memcpy(codec_par->extradata, side_data, codec_par->extradata_size);
+    }
+
     if (apng->frame_number == 0 && !packet) {
         uint8_t *existing_acTL_chunk;
         uint8_t *existing_fcTL_chunk;
@@ -195,11 +209,13 @@ static void flush_packet(AVFormatContext *format_context, AVPacket *packet)
     av_packet_unref(apng->prev_packet);
     if (packet)
         av_copy_packet(apng->prev_packet, packet);
+    return 0;
 }
 
 static int apng_write_packet(AVFormatContext *format_context, AVPacket *packet)
 {
     APNGMuxContext *apng = format_context->priv_data;
+    int ret;
 
     if (!apng->prev_packet) {
         apng->prev_packet = av_malloc(sizeof(*apng->prev_packet));
@@ -208,7 +224,9 @@ static int apng_write_packet(AVFormatContext *format_context, AVPacket *packet)
 
         av_copy_packet(apng->prev_packet, packet);
     } else {
-        flush_packet(format_context, packet);
+        ret = flush_packet(format_context, packet);
+        if (ret < 0)
+            return ret;
     }
 
     return 0;
@@ -219,10 +237,13 @@ static int apng_write_trailer(AVFormatContext *format_context)
     APNGMuxContext *apng = format_context->priv_data;
     AVIOContext *io_context = format_context->pb;
     uint8_t buf[8];
+    int ret;
 
     if (apng->prev_packet) {
-        flush_packet(format_context, NULL);
+        ret = flush_packet(format_context, NULL);
         av_freep(&apng->prev_packet);
+        if (ret < 0)
+            return ret;
     }
 
     apng_write_chunk(io_context, MKBETAG('I', 'E', 'N', 'D'), NULL, 0);
-- 
2.9.3


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