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  1. Member
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    Why is it when I convert one of my m2ts video files to HD AVI it decreases the bit rate and video size, whereas if I convert that same m2ts video to just plain AVI (i.e. NOT HD AVI), it basically keeps it the same bitrate & video size (maybe even expands it a few bytes)? In fact, all the conversions to HD video seem to be a smaller bitrate. I would think that since it is converting to HD, it would be the same bitrate, not significantly smaller. Isn't this decreasing the video quality?
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  2. Member edDV's Avatar
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    Originally Posted by jbitakis View Post
    Why is it when I convert one of my m2ts video files to HD AVI it decreases the bit rate and video size, whereas if I convert that same m2ts video to just plain AVI (i.e. NOT HD AVI), it basically keeps it the same bitrate & video size (maybe even expands it a few bytes)? In fact, all the conversions to HD video seem to be a smaller bitrate. I would think that since it is converting to HD, it would be the same bitrate, not significantly smaller. Isn't this decreasing the video quality?
    HD AVI could mean many things.

    "Converting AVCHD to HD" is meaningless. AVCHD is HD by definition.

    There are codecs (encoder-decoder) that compress the video (e.g. AVCHD video codec is h.264 and audio is AC3 both encoded in the camcorder hardware).

    Then there are containers. Think envelope containing video and audio clips (e.g. AVCHD uses a m2ts/mts transport stream wrapper). A transport stream is a very robust packetized container with heavy duty error recovery used for recording or broadcast (think FedEx envelope with tracking number). Transport stream containers have a small amount of overhead that adds some extra file size vs other containers (avi, mpg, mp4, mkv, mxf, etc).

    When you say AVI you are describing a container. The audio and video codecs inside could be many from fully uncompressed to DV, to xvid. You need to state the a/v codecs to complete the description (e.g. DV, MJPEG, MPeg, xvid, divx, pcm, mp2, ac3, etc).

    You can change containers without changing the video or audio streams. If you demultiplex (remove container) for an AVCHD file, you are left with separate elementary streams (h.264, AC3 and various metadata).

    For example you might say "I demuxed my AVCHD to an mp4 container). This would imply only the container was changed

    Or you might say "I re-encoded my AVCHD to mp4 for Youtube". This would imply you re-encoded interlace h.264 to a more highly compressed 30p h.264, re-encoded AC3 audio to AAC stereo and placed these into an mp4 container). To add to the description you would include video frame rate and video bit rate. Or you could post mediainfo data for a complete description.
    Last edited by edDV; 1st Dec 2011 at 14:09.
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    So the bottom line is, what is the final bitrate, correct? Because using Full Video Converter Free, I converted my M2ts, 1920x1080 60P, 59FPS, 26Mbps file to an Avi container & I lowered the bitrate to 23Mbps and the video played flawlessly on my standalone bluray player via the USB port from a flash drive. I had to convert it from the M2ts because my bluray does not read M2ts files.

    Correct me if I am wrong, but it seems as though the bitrate needs to be just low enough to be able to be played without stuttering, but at the same time High enough to have the best quality video.
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  4. Member edDV's Avatar
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    Blu-Ray is supposed to be m2ts/mts not avi. Next best supported container is mp4. h.264 in an avi wrapper has problems and is generally not recommended.

    As said before, my Sony player chokes above 25 Mbps.
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    My Blu ray player DOES NOT recognize my m2ts video files. That is why I converted them to AVI. I will try using the mp4. h.264, but like I said before, my bluray played the HD video files wrapped in the avi container without any problems via the usb port on the bluray player.
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  6. Member edDV's Avatar
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    If h.264/ac3 in avi container works with direct playback from root on that player then fine. Mp4 is more likely to work on other players.

    If you author an AVCHD or Blu-Ray disc (e.g. in Vegas/DVDA or MultiAVCHD) the result will have an m2ts/mts wrapper since that is the spec.
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  7. sO great reply.

    Originally Posted by edDV View Post
    Originally Posted by jbitakis View Post
    Why is it when I convert one of my m2ts video files to HD AVI it decreases the bit rate and video size, whereas if I convert that same m2ts video to just plain AVI (i.e. NOT HD AVI), it basically keeps it the same bitrate & video size (maybe even expands it a few bytes)? In fact, all the conversions to HD video seem to be a smaller bitrate. I would think that since it is converting to HD, it would be the same bitrate, not significantly smaller. Isn't this decreasing the video quality?
    HD AVI could mean many things.

    "Converting AVCHD to HD" is meaningless. AVCHD is HD by definition.

    There are codecs (encoder-decoder) that compress the video (e.g. AVCHD video codec is h.264 and audio is AC3 both encoded in the camcorder hardware).

    Then there are containers. Think envelope containing video and audio clips (e.g. AVCHD uses a m2ts/mts transport stream wrapper). A transport stream is a very robust packetized container with heavy duty error recovery used for recording or broadcast (think FedEx envelope with tracking number). Transport stream containers have a small amount of overhead that adds some extra file size vs other containers (avi, mpg, mp4, mkv, mxf, etc).

    When you say AVI you are describing a container. The audio and video codecs inside could be many from fully uncompressed to DV, to xvid. You need to state the a/v codecs to complete the description (e.g. DV, MJPEG, MPeg, xvid, divx, pcm, mp2, ac3, etc).

    You can change containers without changing the video or audio streams. If you demultiplex (remove container) for an AVCHD file, you are left with separate elementary streams (h.264, AC3 and various metadata).

    For example you might say "I demuxed my AVCHD to an mp4 container). This would imply only the container was changed

    Or you might say "I re-encoded my AVCHD to mp4 for Youtube". This would imply you re-encoded interlace h.264 to a more highly compressed 30p h.264, re-encoded AC3 audio to AAC stereo and placed these into an mp4 container). To add to the description you would include video frame rate and video bit rate. Or you could post mediainfo data for a complete description.
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