@@ -125,21 +125,24 @@ static int noise(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const ch

     return 1;

 }

+#define MP3_MASK 0xFFFE0CCF

+

 static int mp3_header_compress(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 mode_extension;

+    uint32_t header, extraheader;

+    int mode_extension, header_size;

     if(avctx->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL){

         av_log(avctx, AV_LOG_ERROR, "not standards compliant\n");

         return -1;

     }

-    header = (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3];

+    header = BE_32(buf);

     mode_extension= (header>>4)&3;

-    if(ff_mpa_check_header(header) < 0 || (header&0x70000) != 0x30000){

+    if(ff_mpa_check_header(header) < 0 || (header&0x60000) != 0x20000){

+output_unchanged:

         *poutbuf= (uint8_t *) buf;

         *poutbuf_size= buf_size;

@@ -147,9 +150,25 @@ static int mp3_header_compress(AVBitStreamFilterContext *bsfc, AVCodecContext *a

         return 0;

     }

-    *poutbuf_size= buf_size - 4;

-    *poutbuf= av_malloc(buf_size - 4 + FF_INPUT_BUFFER_PADDING_SIZE);

-    memcpy(*poutbuf, buf + 4, buf_size - 4 + FF_INPUT_BUFFER_PADDING_SIZE);

+    if(avctx->extradata_size == 0){

+        avctx->extradata_size=15;

+        avctx->extradata= av_malloc(avctx->extradata_size);

+        strcpy(avctx->extradata, "FFCMP3 0.0");

+        memcpy(avctx->extradata+11, buf, 4);

+    }

+    if(avctx->extradata_size != 15){

+        av_log(avctx, AV_LOG_ERROR, "Extradata invalid\n");

+        return -1;

+    }

+    extraheader = BE_32(avctx->extradata+11);

+    if((extraheader&MP3_MASK) != (header&MP3_MASK))

+        goto output_unchanged;

+

+    header_size= (header&0x10000) ? 4 : 6;

+

+    *poutbuf_size= buf_size - header_size;

+    *poutbuf= av_malloc(buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE);

+    memcpy(*poutbuf, buf + header_size, buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE);

     if(avctx->channels==2){

         if((header & (3<<19)) != 3<<19){

@@ -173,7 +192,7 @@ static int mp3_header_decompress(AVBitStreamFilterContext *bsfc, AVCodecContext

     int sample_rate_index=0;

     int lsf, mpeg25, bitrate_index, frame_size;

-    header = (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3];

+    header = BE_32(buf);

     if(ff_mpa_check_header(header) >= 0){

         *poutbuf= (uint8_t *) buf;

         *poutbuf_size= buf_size;

@@ -181,18 +200,16 @@ static int mp3_header_decompress(AVBitStreamFilterContext *bsfc, AVCodecContext

         return 0;

     }

-    header= 0xFFE00000 | ((4-3)<<17) | (1<<16); //FIXME simplify

+    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= BE_32(avctx->extradata+11) & MP3_MASK;

     lsf     = sample_rate < (24000+32000)/2;

     mpeg25  = sample_rate < (12000+16000)/2;

-    header |= (!mpeg25)<<20;

-    header |= (!lsf   )<<19;

-    if(sample_rate<<(lsf+mpeg25) < (44100+32000)/2)

-        sample_rate_index |= 2;

-    else if(sample_rate<<(lsf+mpeg25) > (44100+48000)/2)

-        sample_rate_index |= 1;

-

-    header |= sample_rate_index<<10;

+    sample_rate_index= (header>>10)&3;

     sample_rate= 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++){

@@ -200,6 +217,8 @@ static int mp3_header_decompress(AVBitStreamFilterContext *bsfc, AVCodecContext

         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, "couldnt find bitrate_index\n");

@@ -208,18 +227,19 @@ static int mp3_header_decompress(AVBitStreamFilterContext *bsfc, AVCodecContext

     header |= (bitrate_index&1)<<9;

     header |= (bitrate_index>>1)<<12;

-    header |= (avctx->channels==1 ? MPA_MONO : MPA_JSTEREO)<<6;

+    header |= (frame_size == buf_size + 4)<<16; //FIXME actually set a correct crc instead of 0

-    *poutbuf_size= buf_size + 4;

-    *poutbuf= av_malloc(buf_size + 4 + FF_INPUT_BUFFER_PADDING_SIZE);

-    memcpy(*poutbuf + 4, buf, buf_size + FF_INPUT_BUFFER_PADDING_SIZE);

+    *poutbuf_size= frame_size;

+    *poutbuf= av_malloc(frame_size + FF_INPUT_BUFFER_PADDING_SIZE);

+    memcpy(*poutbuf + frame_size - buf_size, buf, buf_size + FF_INPUT_BUFFER_PADDING_SIZE);

     if(avctx->channels==2){

+        uint8_t *p= *poutbuf + frame_size - buf_size;

         if(lsf){

-            FFSWAP(int, (*poutbuf)[5], (*poutbuf)[6]);

-            header |= ((*poutbuf)[5] & 0xC0)>>2;

+            FFSWAP(int, p[1], p[2]);

+            header |= (p[1] & 0xC0)>>2;

         }else{

-            header |= (*poutbuf)[5] & 0x30;

+            header |= p[1] & 0x30;

         }

     }