1 files changed, 124 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..22c1ef0220
--- /dev/null
+++ b/libavcodec/mp3_header_decompress_bsf.c
@@ -0,0 +1,124 @@
+/*
+ * 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 "bsf.h"
+#include "mpegaudiodecheader.h"
+#include "mpegaudiodata.h"
+
+
+static int mp3_header_decompress(AVBSFContext *ctx, AVPacket *out)
+{
+    AVPacket *in;
+    uint32_t header;
+    int sample_rate= ctx->par_in->sample_rate;
+    int sample_rate_index=0;
+    int lsf, mpeg25, bitrate_index, frame_size, ret;
+    uint8_t *buf;
+    int buf_size;
+
+    ret = ff_bsf_get_packet(ctx, &in);
+    if (ret < 0)
+        return ret;
+
+    buf      = in->data;
+    buf_size = in->size;
+
+    header = AV_RB32(buf);
+    if(ff_mpa_check_header(header) >= 0){
+        av_packet_move_ref(out, in);
+        av_packet_free(&in);
+
+        return 0;
+    }
+
+    if(ctx->par_in->extradata_size != 15 || strcmp(ctx->par_in->extradata, "FFCMP3 0.0")){
+        av_log(ctx, AV_LOG_ERROR, "Extradata invalid %d\n", ctx->par_in->extradata_size);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    header= AV_RB32(ctx->par_in->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(ctx, AV_LOG_ERROR, "Could not find bitrate_index.\n");
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    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
+
+    ret = av_new_packet(out, frame_size);
+    if (ret < 0)
+        goto fail;
+    ret = av_packet_copy_props(out, in);
+    if (ret < 0) {
+        av_packet_free(&out);
+        goto fail;
+    }
+    memcpy(out->data + frame_size - buf_size, buf, buf_size + AV_INPUT_BUFFER_PADDING_SIZE);
+
+    if(ctx->par_in->channels==2){
+        uint8_t *p= out->data + 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(out->data, header);
+
+    ret = 0;
+
+fail:
+    av_packet_free(&in);
+    return ret;
+}
+
+static const enum AVCodecID codec_ids[] = {
+    AV_CODEC_ID_MP3, AV_CODEC_ID_NONE,
+};
+
+const AVBitStreamFilter ff_mp3_header_decompress_bsf = {
+    .name      = "mp3decomp",
+    .filter    = mp3_header_decompress,
+    .codec_ids = codec_ids,
+};