1 files changed, 97 insertions, 0 deletions
diff --git a/libavcodec/mp3_header_decompress_bsf.c b/libavcodec/mp3_header_decompress_bsf.c
new file mode 100644
index 0000000000..95c0b5b769
--- /dev/null
+++ b/libavcodec/mp3_header_decompress_bsf.c
@@ -0,0 +1,97 @@
+/*
+ * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/common.h"
+#include "libavutil/intreadwrite.h"
+#include "avcodec.h"
+#include "mpegaudiodecheader.h"
+#include "mpegaudiodata.h"
+
+
+static int mp3_header_decompress(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args,
+                     uint8_t **poutbuf, int *poutbuf_size,
+                     const uint8_t *buf, int buf_size, int keyframe){
+    uint32_t header;
+    int sample_rate= avctx->sample_rate;
+    int sample_rate_index=0;
+    int lsf, mpeg25, bitrate_index, frame_size;
+
+    header = AV_RB32(buf);
+    if(ff_mpa_check_header(header) >= 0){
+        *poutbuf= (uint8_t *) buf;
+        *poutbuf_size= buf_size;
+
+        return 0;
+    }
+
+    if(avctx->extradata_size != 15 || strcmp(avctx->extradata, "FFCMP3 0.0")){
+        av_log(avctx, AV_LOG_ERROR, "Extradata invalid %d\n", avctx->extradata_size);
+        return -1;
+    }
+
+    header= AV_RB32(avctx->extradata+11) & MP3_MASK;
+
+    lsf     = sample_rate < (24000+32000)/2;
+    mpeg25  = sample_rate < (12000+16000)/2;
+    sample_rate_index= (header>>10)&3;
+    sample_rate= avpriv_mpa_freq_tab[sample_rate_index] >> (lsf + mpeg25); //in case sample rate is a little off
+
+    for(bitrate_index=2; bitrate_index<30; bitrate_index++){
+        frame_size = avpriv_mpa_bitrate_tab[lsf][2][bitrate_index>>1];
+        frame_size = (frame_size * 144000) / (sample_rate << lsf) + (bitrate_index&1);
+        if(frame_size == buf_size + 4)
+            break;
+        if(frame_size == buf_size + 6)
+            break;
+    }
+    if(bitrate_index == 30){
+        av_log(avctx, AV_LOG_ERROR, "Could not find bitrate_index.\n");
+        return -1;
+    }
+
+    header |= (bitrate_index&1)<<9;
+    header |= (bitrate_index>>1)<<12;
+    header |= (frame_size == buf_size + 4)<<16; //FIXME actually set a correct crc instead of 0
+
+    *poutbuf_size= frame_size;
+    *poutbuf= av_malloc(frame_size + AV_INPUT_BUFFER_PADDING_SIZE);
+    memcpy(*poutbuf + frame_size - buf_size, buf, buf_size + AV_INPUT_BUFFER_PADDING_SIZE);
+
+    if(avctx->channels==2){
+        uint8_t *p= *poutbuf + frame_size - buf_size;
+        if(lsf){
+            FFSWAP(int, p[1], p[2]);
+            header |= (p[1] & 0xC0)>>2;
+            p[1] &= 0x3F;
+        }else{
+            header |= p[1] & 0x30;
+            p[1] &= 0xCF;
+        }
+    }
+
+    AV_WB32(*poutbuf, header);
+
+    return 1;
+}
+
+AVBitStreamFilter ff_mp3_header_decompress_bsf={
+    .name   = "mp3decomp",
+    .filter = mp3_header_decompress,
+};