avformat/flvenc: use ff_format_shift_data for data shifting

add_keyframe_index seems to generate a corrupted index even before this change.

Signed-off-by: Marton Balint <cus@passwd.hu>

libavformat/flvenc.c

@@ -576,15 +576,9 @@ static int flv_append_keyframe_info(AVFormatContext *s, FLVContext *flv, double
 
 static int shift_data(AVFormatContext *s)
 {
-    int ret = 0;
-    int n = 0;
+    int ret;
     int64_t metadata_size = 0;
     FLVContext *flv = s->priv_data;
-    int64_t pos, pos_end = avio_tell(s->pb); /* Save the pre-shift size. */
-    uint8_t *buf, *read_buf[2];
-    int read_buf_id = 0;
-    int read_size[2];
-    AVIOContext *read_pb;
 
     metadata_size = flv->filepositions_count * 9 * 2 + 10; /* filepositions and times value */
     metadata_size += 2 + 13; /* filepositions String */
@@ -596,58 +590,17 @@ static int shift_data(AVFormatContext *s)
     if (metadata_size < 0)
         return metadata_size;
 
-    buf = av_malloc_array(metadata_size, 2);
-    if (!buf) {
-        return AVERROR(ENOMEM);
-    }
-    read_buf[0] = buf;
-    read_buf[1] = buf + metadata_size;
+    ret = ff_format_shift_data(s, flv->keyframes_info_offset, metadata_size);
+    if (ret < 0)
+        return ret;
 
     avio_seek(s->pb, flv->metadata_size_pos, SEEK_SET);
     avio_wb24(s->pb, flv->metadata_totalsize + metadata_size);
 
-    avio_seek(s->pb, flv->metadata_totalsize_pos, SEEK_SET);
+    avio_seek(s->pb, flv->metadata_totalsize_pos + metadata_size, SEEK_SET);
     avio_wb32(s->pb, flv->metadata_totalsize + 11 + metadata_size);
 
-    /* Shift the data: the AVIO context of the output can only be used for
-     * writing, so we re-open the same output, but for reading. It also avoids
-     * a read/seek/write/seek back and forth. */
-    avio_flush(s->pb);
-    ret = s->io_open(s, &read_pb, s->url, AVIO_FLAG_READ, NULL);
-    if (ret < 0) {
-        av_log(s, AV_LOG_ERROR, "Unable to re-open %s output file for "
-               "the second pass (add_keyframe_index)\n", s->url);
-        goto end;
-    }
-
-    /* Get ready for writing. */
-    avio_seek(s->pb, flv->keyframes_info_offset + metadata_size, SEEK_SET);
-
-    /* start reading at where the keyframe index information will be placed */
-    avio_seek(read_pb, flv->keyframes_info_offset, SEEK_SET);
-    pos = avio_tell(read_pb);
-
-#define READ_BLOCK do {                                                             \
-    read_size[read_buf_id] = avio_read(read_pb, read_buf[read_buf_id], metadata_size);  \
-    read_buf_id ^= 1;                                                               \
-} while (0)
-
-    /* shift data by chunk of at most keyframe *filepositions* and *times* size */
-    READ_BLOCK;
-    do {
-        READ_BLOCK;
-        n = read_size[read_buf_id];
-        if (n < 0)
-            break;
-        avio_write(s->pb, read_buf[read_buf_id], n);
-        pos += n;
-    } while (pos <= pos_end);
-
-    ff_format_io_close(s, &read_pb);
-
-end:
-    av_free(buf);
-    return ret;
+    return 0;
 }
 
 static int flv_init(struct AVFormatContext *s)